lavf/segment: add deinit function
[ffmpeg.git] / libavcodec / pngenc.c
index a29d3c9..00c830e 100644 (file)
  * License along with FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
+
 #include "avcodec.h"
 #include "internal.h"
 #include "bytestream.h"
-#include "dsputil.h"
+#include "huffyuvencdsp.h"
 #include "png.h"
+#include "apng.h"
 
 #include "libavutil/avassert.h"
-
-/* TODO:
- * - add 2, 4 and 16 bit depth support
- */
+#include "libavutil/crc.h"
+#include "libavutil/libm.h"
+#include "libavutil/opt.h"
+#include "libavutil/color_utils.h"
+#include "libavutil/stereo3d.h"
 
 #include <zlib.h>
 
-//#define DEBUG
-
 #define IOBUF_SIZE 4096
 
+typedef struct APNGFctlChunk {
+    uint32_t sequence_number;
+    uint32_t width, height;
+    uint32_t x_offset, y_offset;
+    uint16_t delay_num, delay_den;
+    uint8_t dispose_op, blend_op;
+} APNGFctlChunk;
+
 typedef struct PNGEncContext {
-    DSPContext dsp;
+    AVClass *class;
+    HuffYUVEncDSPContext hdsp;
 
     uint8_t *bytestream;
     uint8_t *bytestream_start;
     uint8_t *bytestream_end;
-    AVFrame picture;
 
     int filter_type;
 
     z_stream zstream;
     uint8_t buf[IOBUF_SIZE];
+    int dpi;                     ///< Physical pixel density, in dots per inch, if set
+    int dpm;                     ///< Physical pixel density, in dots per meter, if set
+
+    int is_progressive;
+    int bit_depth;
+    int color_type;
+    int bits_per_pixel;
+
+    // APNG
+    uint32_t palette_checksum;   // Used to ensure a single unique palette
+    uint32_t sequence_number;
+
+    AVFrame *prev_frame;
+    AVFrame *last_frame;
+    APNGFctlChunk last_frame_fctl;
+    uint8_t *last_frame_packet;
+    size_t last_frame_packet_size;
 } PNGEncContext;
 
 static void png_get_interlaced_row(uint8_t *dst, int row_size,
@@ -57,13 +83,14 @@ static void png_get_interlaced_row(uint8_t *dst, int row_size,
     int x, mask, dst_x, j, b, bpp;
     uint8_t *d;
     const uint8_t *s;
+    static const int masks[] = {0x80, 0x08, 0x88, 0x22, 0xaa, 0x55, 0xff};
 
-    mask =  (int[]){0x80, 0x08, 0x88, 0x22, 0xaa, 0x55, 0xff}[pass];
-    switch(bits_per_pixel) {
+    mask = masks[pass];
+    switch (bits_per_pixel) {
     case 1:
         memset(dst, 0, row_size);
         dst_x = 0;
-        for(x = 0; x < width; x++) {
+        for (x = 0; x < width; x++) {
             j = (x & 7);
             if ((mask << j) & 0x80) {
                 b = (src[x >> 3] >> (7 - j)) & 1;
@@ -76,7 +103,7 @@ static void png_get_interlaced_row(uint8_t *dst, int row_size,
         bpp = bits_per_pixel >> 3;
         d = dst;
         s = src;
-        for(x = 0; x < width; x++) {
+        for (x = 0; x < width; x++) {
             j = x & 7;
             if ((mask << j) & 0x80) {
                 memcpy(d, s, bpp);
@@ -88,17 +115,18 @@ static void png_get_interlaced_row(uint8_t *dst, int row_size,
     }
 }
 
-static void sub_png_paeth_prediction(uint8_t *dst, uint8_t *src, uint8_t *top, int w, int bpp)
+static void sub_png_paeth_prediction(uint8_t *dst, uint8_t *src, uint8_t *top,
+                                     int w, int bpp)
 {
     int i;
-    for(i = 0; i < w; i++) {
+    for (i = 0; i < w; i++) {
         int a, b, c, p, pa, pb, pc;
 
         a = src[i - bpp];
         b = top[i];
         c = top[i - bpp];
 
-        p = b - c;
+        p  = b - c;
         pc = a - c;
 
         pa = abs(p);
@@ -115,32 +143,47 @@ static void sub_png_paeth_prediction(uint8_t *dst, uint8_t *src, uint8_t *top, i
     }
 }
 
-static void png_filter_row(DSPContext *dsp, uint8_t *dst, int filter_type,
+static void sub_left_prediction(PNGEncContext *c, uint8_t *dst, const uint8_t *src, int bpp, int size)
+{
+    const uint8_t *src1 = src + bpp;
+    const uint8_t *src2 = src;
+    int x, unaligned_w;
+
+    memcpy(dst, src, bpp);
+    dst += bpp;
+    size -= bpp;
+    unaligned_w = FFMIN(32 - bpp, size);
+    for (x = 0; x < unaligned_w; x++)
+        *dst++ = *src1++ - *src2++;
+    size -= unaligned_w;
+    c->hdsp.diff_bytes(dst, src1, src2, size);
+}
+
+static void png_filter_row(PNGEncContext *c, uint8_t *dst, int filter_type,
                            uint8_t *src, uint8_t *top, int size, int bpp)
 {
     int i;
 
-    switch(filter_type) {
+    switch (filter_type) {
     case PNG_FILTER_VALUE_NONE:
         memcpy(dst, src, size);
         break;
     case PNG_FILTER_VALUE_SUB:
-        dsp->diff_bytes(dst, src, src-bpp, size);
-        memcpy(dst, src, bpp);
+        sub_left_prediction(c, dst, src, bpp, size);
         break;
     case PNG_FILTER_VALUE_UP:
-        dsp->diff_bytes(dst, src, top, size);
+        c->hdsp.diff_bytes(dst, src, top, size);
         break;
     case PNG_FILTER_VALUE_AVG:
-        for(i = 0; i < bpp; i++)
+        for (i = 0; i < bpp; i++)
             dst[i] = src[i] - (top[i] >> 1);
-        for(; i < size; i++)
-            dst[i] = src[i] - ((src[i-bpp] + top[i]) >> 1);
+        for (; i < size; i++)
+            dst[i] = src[i] - ((src[i - bpp] + top[i]) >> 1);
         break;
     case PNG_FILTER_VALUE_PAETH:
-        for(i = 0; i < bpp; i++)
+        for (i = 0; i < bpp; i++)
             dst[i] = src[i] - top[i];
-        sub_png_paeth_prediction(dst+i, src+i, top+i, size-i, bpp);
+        sub_png_paeth_prediction(dst + i, src + i, top + i, size - i, bpp);
         break;
     }
 }
@@ -150,26 +193,26 @@ static uint8_t *png_choose_filter(PNGEncContext *s, uint8_t *dst,
 {
     int pred = s->filter_type;
     av_assert0(bpp || !pred);
-    if(!top && pred)
+    if (!top && pred)
         pred = PNG_FILTER_VALUE_SUB;
-    if(pred == PNG_FILTER_VALUE_MIXED) {
+    if (pred == PNG_FILTER_VALUE_MIXED) {
         int i;
         int cost, bcost = INT_MAX;
         uint8_t *buf1 = dst, *buf2 = dst + size + 16;
-        for(pred=0; pred<5; pred++) {
-            png_filter_row(&s->dsp, buf1+1, pred, src, top, size, bpp);
+        for (pred = 0; pred < 5; pred++) {
+            png_filter_row(s, buf1 + 1, pred, src, top, size, bpp);
             buf1[0] = pred;
             cost = 0;
-            for(i=0; i<=size; i++)
-                cost += abs((int8_t)buf1[i]);
-            if(cost < bcost) {
+            for (i = 0; i <= size; i++)
+                cost += abs((int8_t) buf1[i]);
+            if (cost < bcost) {
                 bcost = cost;
-                FFSWAP(uint8_t*, buf1, buf2);
+                FFSWAP(uint8_t *, buf1, buf2);
             }
         }
         return buf2;
     } else {
-        png_filter_row(&s->dsp, dst+1, pred, src, top, size, bpp);
+        png_filter_row(s, dst + 1, pred, src, top, size, bpp);
         dst[0] = pred;
         return dst;
     }
@@ -178,285 +221,948 @@ static uint8_t *png_choose_filter(PNGEncContext *s, uint8_t *dst,
 static void png_write_chunk(uint8_t **f, uint32_t tag,
                             const uint8_t *buf, int length)
 {
-    uint32_t crc;
+    const AVCRC *crc_table = av_crc_get_table(AV_CRC_32_IEEE_LE);
+    uint32_t crc = ~0U;
     uint8_t tagbuf[4];
 
     bytestream_put_be32(f, length);
-    crc = crc32(0, Z_NULL, 0);
     AV_WL32(tagbuf, tag);
-    crc = crc32(crc, tagbuf, 4);
+    crc = av_crc(crc_table, crc, tagbuf, 4);
     bytestream_put_be32(f, av_bswap32(tag));
     if (length > 0) {
-        crc = crc32(crc, buf, length);
+        crc = av_crc(crc_table, crc, buf, length);
         memcpy(*f, buf, length);
         *f += length;
     }
-    bytestream_put_be32(f, crc);
+    bytestream_put_be32(f, ~crc);
+}
+
+static void png_write_image_data(AVCodecContext *avctx,
+                                 const uint8_t *buf, int length)
+{
+    PNGEncContext *s = avctx->priv_data;
+    const AVCRC *crc_table = av_crc_get_table(AV_CRC_32_IEEE_LE);
+    uint32_t crc = ~0U;
+
+    if (avctx->codec_id == AV_CODEC_ID_PNG || avctx->frame_number == 0) {
+        png_write_chunk(&s->bytestream, MKTAG('I', 'D', 'A', 'T'), buf, length);
+        return;
+    }
+
+    bytestream_put_be32(&s->bytestream, length + 4);
+
+    bytestream_put_be32(&s->bytestream, MKBETAG('f', 'd', 'A', 'T'));
+    bytestream_put_be32(&s->bytestream, s->sequence_number);
+    crc = av_crc(crc_table, crc, s->bytestream - 8, 8);
+
+    crc = av_crc(crc_table, crc, buf, length);
+    memcpy(s->bytestream, buf, length);
+    s->bytestream += length;
+
+    bytestream_put_be32(&s->bytestream, ~crc);
+
+    ++s->sequence_number;
 }
 
 /* XXX: do filtering */
-static int png_write_row(PNGEncContext *s, const uint8_t *data, int size)
+static int png_write_row(AVCodecContext *avctx, const uint8_t *data, int size)
 {
+    PNGEncContext *s = avctx->priv_data;
     int ret;
 
     s->zstream.avail_in = size;
-    s->zstream.next_in = (uint8_t *)data;
+    s->zstream.next_in  = data;
     while (s->zstream.avail_in > 0) {
         ret = deflate(&s->zstream, Z_NO_FLUSH);
         if (ret != Z_OK)
             return -1;
         if (s->zstream.avail_out == 0) {
-            if(s->bytestream_end - s->bytestream > IOBUF_SIZE + 100)
-                png_write_chunk(&s->bytestream, MKTAG('I', 'D', 'A', 'T'), s->buf, IOBUF_SIZE);
+            if (s->bytestream_end - s->bytestream > IOBUF_SIZE + 100)
+                png_write_image_data(avctx, s->buf, IOBUF_SIZE);
             s->zstream.avail_out = IOBUF_SIZE;
-            s->zstream.next_out = s->buf;
+            s->zstream.next_out  = s->buf;
         }
     }
     return 0;
 }
 
-static int encode_frame(AVCodecContext *avctx, AVPacket *pkt,
-                        const AVFrame *pict, int *got_packet)
+#define AV_WB32_PNG(buf, n) AV_WB32(buf, lrint((n) * 100000))
+static int png_get_chrm(enum AVColorPrimaries prim,  uint8_t *buf)
 {
-    PNGEncContext *s = avctx->priv_data;
-    AVFrame * const p= &s->picture;
-    int bit_depth, color_type, y, len, row_size, ret, is_progressive;
-    int bits_per_pixel, pass_row_size, enc_row_size;
-    int64_t max_packet_size;
-    int compression_level;
-    uint8_t *ptr, *top;
-    uint8_t *crow_base = NULL, *crow_buf, *crow;
-    uint8_t *progressive_buf = NULL;
-    uint8_t *top_buf = NULL;
-
-    *p = *pict;
-    p->pict_type= AV_PICTURE_TYPE_I;
-    p->key_frame= 1;
-
-    is_progressive = !!(avctx->flags & CODEC_FLAG_INTERLACED_DCT);
-    switch(avctx->pix_fmt) {
-    case PIX_FMT_RGBA64BE:
-        bit_depth = 16;
-        color_type = PNG_COLOR_TYPE_RGB_ALPHA;
-        break;
-    case PIX_FMT_RGB48BE:
-        bit_depth = 16;
-        color_type = PNG_COLOR_TYPE_RGB;
-        break;
-    case PIX_FMT_RGBA:
-        avctx->bits_per_coded_sample = 32;
-        bit_depth = 8;
-        color_type = PNG_COLOR_TYPE_RGB_ALPHA;
-        break;
-    case PIX_FMT_RGB24:
-        avctx->bits_per_coded_sample = 24;
-        bit_depth = 8;
-        color_type = PNG_COLOR_TYPE_RGB;
-        break;
-    case PIX_FMT_GRAY16BE:
-        bit_depth = 16;
-        color_type = PNG_COLOR_TYPE_GRAY;
-        break;
-    case PIX_FMT_GRAY8:
-        avctx->bits_per_coded_sample = 0x28;
-        bit_depth = 8;
-        color_type = PNG_COLOR_TYPE_GRAY;
-        break;
-    case PIX_FMT_GRAY8A:
-        bit_depth = 8;
-        color_type = PNG_COLOR_TYPE_GRAY_ALPHA;
-        break;
-    case PIX_FMT_MONOBLACK:
-        avctx->bits_per_coded_sample =
-        bit_depth = 1;
-        color_type = PNG_COLOR_TYPE_GRAY;
-        break;
-    case PIX_FMT_PAL8:
-        avctx->bits_per_coded_sample =
-        bit_depth = 8;
-        color_type = PNG_COLOR_TYPE_PALETTE;
-        break;
-    default:
-        return -1;
+    double rx, ry, gx, gy, bx, by, wx = 0.3127, wy = 0.3290;
+    switch (prim) {
+        case AVCOL_PRI_BT709:
+            rx = 0.640; ry = 0.330;
+            gx = 0.300; gy = 0.600;
+            bx = 0.150; by = 0.060;
+            break;
+        case AVCOL_PRI_BT470M:
+            rx = 0.670; ry = 0.330;
+            gx = 0.210; gy = 0.710;
+            bx = 0.140; by = 0.080;
+            wx = 0.310; wy = 0.316;
+            break;
+        case AVCOL_PRI_BT470BG:
+            rx = 0.640; ry = 0.330;
+            gx = 0.290; gy = 0.600;
+            bx = 0.150; by = 0.060;
+            break;
+        case AVCOL_PRI_SMPTE170M:
+        case AVCOL_PRI_SMPTE240M:
+            rx = 0.630; ry = 0.340;
+            gx = 0.310; gy = 0.595;
+            bx = 0.155; by = 0.070;
+            break;
+        case AVCOL_PRI_BT2020:
+            rx = 0.708; ry = 0.292;
+            gx = 0.170; gy = 0.797;
+            bx = 0.131; by = 0.046;
+            break;
+        default:
+            return 0;
     }
-    bits_per_pixel = ff_png_get_nb_channels(color_type) * bit_depth;
-    row_size = (avctx->width * bits_per_pixel + 7) >> 3;
 
-    s->zstream.zalloc = ff_png_zalloc;
-    s->zstream.zfree = ff_png_zfree;
-    s->zstream.opaque = NULL;
-    compression_level = avctx->compression_level == FF_COMPRESSION_DEFAULT ?
-                            Z_DEFAULT_COMPRESSION :
-                            av_clip(avctx->compression_level, 0, 9);
-    ret = deflateInit2(&s->zstream, compression_level,
-                       Z_DEFLATED, 15, 8, Z_DEFAULT_STRATEGY);
-    if (ret != Z_OK)
-        return -1;
+    AV_WB32_PNG(buf     , wx); AV_WB32_PNG(buf + 4 , wy);
+    AV_WB32_PNG(buf + 8 , rx); AV_WB32_PNG(buf + 12, ry);
+    AV_WB32_PNG(buf + 16, gx); AV_WB32_PNG(buf + 20, gy);
+    AV_WB32_PNG(buf + 24, bx); AV_WB32_PNG(buf + 28, by);
+    return 1;
+}
 
-    enc_row_size    = deflateBound(&s->zstream, row_size);
-    max_packet_size = avctx->height * (int64_t)(enc_row_size +
-                                       ((enc_row_size + IOBUF_SIZE - 1) / IOBUF_SIZE) * 12)
-                      + FF_MIN_BUFFER_SIZE;
-    if (max_packet_size > INT_MAX)
-        return AVERROR(ENOMEM);
-    if ((ret = ff_alloc_packet2(avctx, pkt, max_packet_size)) < 0)
-        return ret;
+static int png_get_gama(enum AVColorTransferCharacteristic trc, uint8_t *buf)
+{
+    double gamma = avpriv_get_gamma_from_trc(trc);
+    if (gamma <= 1e-6)
+        return 0;
 
-    s->bytestream_start =
-    s->bytestream       = pkt->data;
-    s->bytestream_end   = pkt->data + pkt->size;
+    AV_WB32_PNG(buf, 1.0 / gamma);
+    return 1;
+}
 
-    crow_base = av_malloc((row_size + 32) << (s->filter_type == PNG_FILTER_VALUE_MIXED));
-    if (!crow_base)
-        goto fail;
-    crow_buf = crow_base + 15; // pixel data should be aligned, but there's a control byte before it
-    if (is_progressive) {
-        progressive_buf = av_malloc(row_size + 1);
-        if (!progressive_buf)
-            goto fail;
-    }
-    if (is_progressive) {
-        top_buf = av_malloc(row_size + 1);
-        if (!top_buf)
-            goto fail;
-    }
+static int encode_headers(AVCodecContext *avctx, const AVFrame *pict)
+{
+    AVFrameSideData *side_data;
+    PNGEncContext *s = avctx->priv_data;
 
     /* write png header */
-    AV_WB64(s->bytestream, PNGSIG);
-    s->bytestream += 8;
-
     AV_WB32(s->buf, avctx->width);
     AV_WB32(s->buf + 4, avctx->height);
-    s->buf[8] bit_depth;
-    s->buf[9] color_type;
+    s->buf[8]  = s->bit_depth;
+    s->buf[9]  = s->color_type;
     s->buf[10] = 0; /* compression type */
     s->buf[11] = 0; /* filter type */
-    s->buf[12] = is_progressive; /* interlace type */
-
+    s->buf[12] = s->is_progressive; /* interlace type */
     png_write_chunk(&s->bytestream, MKTAG('I', 'H', 'D', 'R'), s->buf, 13);
 
+    /* write physical information */
+    if (s->dpm) {
+      AV_WB32(s->buf, s->dpm);
+      AV_WB32(s->buf + 4, s->dpm);
+      s->buf[8] = 1; /* unit specifier is meter */
+    } else {
+      AV_WB32(s->buf, avctx->sample_aspect_ratio.num);
+      AV_WB32(s->buf + 4, avctx->sample_aspect_ratio.den);
+      s->buf[8] = 0; /* unit specifier is unknown */
+    }
+    png_write_chunk(&s->bytestream, MKTAG('p', 'H', 'Y', 's'), s->buf, 9);
+
+    /* write stereoscopic information */
+    side_data = av_frame_get_side_data(pict, AV_FRAME_DATA_STEREO3D);
+    if (side_data) {
+        AVStereo3D *stereo3d = (AVStereo3D *)side_data->data;
+        switch (stereo3d->type) {
+            case AV_STEREO3D_SIDEBYSIDE:
+                s->buf[0] = ((stereo3d->flags & AV_STEREO3D_FLAG_INVERT) == 0) ? 1 : 0;
+                png_write_chunk(&s->bytestream, MKTAG('s', 'T', 'E', 'R'), s->buf, 1);
+                break;
+            case AV_STEREO3D_2D:
+                break;
+            default:
+                av_log(avctx, AV_LOG_WARNING, "Only side-by-side stereo3d flag can be defined within sTER chunk\n");
+                break;
+        }
+    }
+
+    /* write colorspace information */
+    if (pict->color_primaries == AVCOL_PRI_BT709 &&
+        pict->color_trc == AVCOL_TRC_IEC61966_2_1) {
+        s->buf[0] = 1; /* rendering intent, relative colorimetric by default */
+        png_write_chunk(&s->bytestream, MKTAG('s', 'R', 'G', 'B'), s->buf, 1);
+    }
+
+    if (png_get_chrm(pict->color_primaries, s->buf))
+        png_write_chunk(&s->bytestream, MKTAG('c', 'H', 'R', 'M'), s->buf, 32);
+    if (png_get_gama(pict->color_trc, s->buf))
+        png_write_chunk(&s->bytestream, MKTAG('g', 'A', 'M', 'A'), s->buf, 4);
+
     /* put the palette if needed */
-    if (color_type == PNG_COLOR_TYPE_PALETTE) {
+    if (s->color_type == PNG_COLOR_TYPE_PALETTE) {
         int has_alpha, alpha, i;
         unsigned int v;
         uint32_t *palette;
-        uint8_t *alpha_ptr;
+        uint8_t *ptr, *alpha_ptr;
 
-        palette = (uint32_t *)p->data[1];
-        ptr = s->buf;
+        palette   = (uint32_t *)pict->data[1];
+        ptr       = s->buf;
         alpha_ptr = s->buf + 256 * 3;
         has_alpha = 0;
-        for(i = 0; i < 256; i++) {
-            v = palette[i];
+        for (i = 0; i < 256; i++) {
+            v     = palette[i];
             alpha = v >> 24;
             if (alpha != 0xff)
                 has_alpha = 1;
             *alpha_ptr++ = alpha;
             bytestream_put_be24(&ptr, v);
         }
-        png_write_chunk(&s->bytestream, MKTAG('P', 'L', 'T', 'E'), s->buf, 256 * 3);
+        png_write_chunk(&s->bytestream,
+                        MKTAG('P', 'L', 'T', 'E'), s->buf, 256 * 3);
         if (has_alpha) {
-            png_write_chunk(&s->bytestream, MKTAG('t', 'R', 'N', 'S'), s->buf + 256 * 3, 256);
+            png_write_chunk(&s->bytestream,
+                            MKTAG('t', 'R', 'N', 'S'), s->buf + 256 * 3, 256);
+        }
+    }
+
+    return 0;
+}
+
+static int encode_frame(AVCodecContext *avctx, const AVFrame *pict)
+{
+    PNGEncContext *s       = avctx->priv_data;
+    const AVFrame *const p = pict;
+    int y, len, ret;
+    int row_size, pass_row_size;
+    uint8_t *ptr, *top, *crow_buf, *crow;
+    uint8_t *crow_base       = NULL;
+    uint8_t *progressive_buf = NULL;
+    uint8_t *top_buf         = NULL;
+
+    row_size = (pict->width * s->bits_per_pixel + 7) >> 3;
+
+    crow_base = av_malloc((row_size + 32) << (s->filter_type == PNG_FILTER_VALUE_MIXED));
+    if (!crow_base) {
+        ret = AVERROR(ENOMEM);
+        goto the_end;
+    }
+    // pixel data should be aligned, but there's a control byte before it
+    crow_buf = crow_base + 15;
+    if (s->is_progressive) {
+        progressive_buf = av_malloc(row_size + 1);
+        top_buf = av_malloc(row_size + 1);
+        if (!progressive_buf || !top_buf) {
+            ret = AVERROR(ENOMEM);
+            goto the_end;
         }
     }
 
-    /* now put each row */
+    /* put each row */
     s->zstream.avail_out = IOBUF_SIZE;
-    s->zstream.next_out = s->buf;
-    if (is_progressive) {
+    s->zstream.next_out  = s->buf;
+    if (s->is_progressive) {
         int pass;
 
-        for(pass = 0; pass < NB_PASSES; pass++) {
-            /* NOTE: a pass is completely omited if no pixels would be
-               output */
-            pass_row_size = ff_png_pass_row_size(pass, bits_per_pixel, avctx->width);
+        for (pass = 0; pass < NB_PASSES; pass++) {
+            /* NOTE: a pass is completely omitted if no pixels would be
+             * output */
+            pass_row_size = ff_png_pass_row_size(pass, s->bits_per_pixel, pict->width);
             if (pass_row_size > 0) {
                 top = NULL;
-                for(y = 0; y < avctx->height; y++) {
+                for (y = 0; y < pict->height; y++)
                     if ((ff_png_pass_ymask[pass] << (y & 7)) & 0x80) {
                         ptr = p->data[0] + y * p->linesize[0];
-                        FFSWAP(uint8_t*, progressive_buf, top_buf);
+                        FFSWAP(uint8_t *, progressive_buf, top_buf);
                         png_get_interlaced_row(progressive_buf, pass_row_size,
-                                               bits_per_pixel, pass,
-                                               ptr, avctx->width);
-                        crow = png_choose_filter(s, crow_buf, progressive_buf, top, pass_row_size, bits_per_pixel>>3);
-                        png_write_row(s, crow, pass_row_size + 1);
+                                               s->bits_per_pixel, pass,
+                                               ptr, pict->width);
+                        crow = png_choose_filter(s, crow_buf, progressive_buf,
+                                                 top, pass_row_size, s->bits_per_pixel >> 3);
+                        png_write_row(avctx, crow, pass_row_size + 1);
                         top = progressive_buf;
                     }
-                }
             }
         }
     } else {
         top = NULL;
-        for(y = 0; y < avctx->height; y++) {
+        for (y = 0; y < pict->height; y++) {
             ptr = p->data[0] + y * p->linesize[0];
-            crow = png_choose_filter(s, crow_buf, ptr, top, row_size, bits_per_pixel>>3);
-            png_write_row(s, crow, row_size + 1);
+            crow = png_choose_filter(s, crow_buf, ptr, top,
+                                     row_size, s->bits_per_pixel >> 3);
+            png_write_row(avctx, crow, row_size + 1);
             top = ptr;
         }
     }
     /* compress last bytes */
-    for(;;) {
+    for (;;) {
         ret = deflate(&s->zstream, Z_FINISH);
         if (ret == Z_OK || ret == Z_STREAM_END) {
             len = IOBUF_SIZE - s->zstream.avail_out;
             if (len > 0 && s->bytestream_end - s->bytestream > len + 100) {
-                png_write_chunk(&s->bytestream, MKTAG('I', 'D', 'A', 'T'), s->buf, len);
+                png_write_image_data(avctx, s->buf, len);
             }
             s->zstream.avail_out = IOBUF_SIZE;
-            s->zstream.next_out = s->buf;
+            s->zstream.next_out  = s->buf;
             if (ret == Z_STREAM_END)
                 break;
         } else {
-            goto fail;
+            ret = -1;
+            goto the_end;
         }
     }
+
+    ret = 0;
+
+the_end:
+    av_freep(&crow_base);
+    av_freep(&progressive_buf);
+    av_freep(&top_buf);
+    deflateReset(&s->zstream);
+    return ret;
+}
+
+static int encode_png(AVCodecContext *avctx, AVPacket *pkt,
+                      const AVFrame *pict, int *got_packet)
+{
+    PNGEncContext *s = avctx->priv_data;
+    int ret;
+    int enc_row_size;
+    size_t max_packet_size;
+
+    enc_row_size    = deflateBound(&s->zstream, (avctx->width * s->bits_per_pixel + 7) >> 3);
+    max_packet_size =
+        AV_INPUT_BUFFER_MIN_SIZE + // headers
+        avctx->height * (
+            enc_row_size +
+            12 * (((int64_t)enc_row_size + IOBUF_SIZE - 1) / IOBUF_SIZE) // IDAT * ceil(enc_row_size / IOBUF_SIZE)
+        );
+    if (max_packet_size > INT_MAX)
+        return AVERROR(ENOMEM);
+    ret = ff_alloc_packet2(avctx, pkt, max_packet_size, 0);
+    if (ret < 0)
+        return ret;
+
+    s->bytestream_start =
+    s->bytestream       = pkt->data;
+    s->bytestream_end   = pkt->data + pkt->size;
+
+    AV_WB64(s->bytestream, PNGSIG);
+    s->bytestream += 8;
+
+    ret = encode_headers(avctx, pict);
+    if (ret < 0)
+        return ret;
+
+    ret = encode_frame(avctx, pict);
+    if (ret < 0)
+        return ret;
+
     png_write_chunk(&s->bytestream, MKTAG('I', 'E', 'N', 'D'), NULL, 0);
 
-    pkt->size   = s->bytestream - s->bytestream_start;
+    pkt->size = s->bytestream - s->bytestream_start;
     pkt->flags |= AV_PKT_FLAG_KEY;
     *got_packet = 1;
-    ret         = 0;
 
- the_end:
-    av_free(crow_base);
-    av_free(progressive_buf);
-    av_free(top_buf);
-    deflateEnd(&s->zstream);
+    return 0;
+}
+
+static int apng_do_inverse_blend(AVFrame *output, const AVFrame *input,
+                                  APNGFctlChunk *fctl_chunk, uint8_t bpp)
+{
+    // output: background, input: foreground
+    // output the image such that when blended with the background, will produce the foreground
+
+    unsigned int x, y;
+    unsigned int leftmost_x = input->width;
+    unsigned int rightmost_x = 0;
+    unsigned int topmost_y = input->height;
+    unsigned int bottommost_y = 0;
+    const uint8_t *input_data = input->data[0];
+    uint8_t *output_data = output->data[0];
+    ptrdiff_t input_linesize = input->linesize[0];
+    ptrdiff_t output_linesize = output->linesize[0];
+
+    // Find bounding box of changes
+    for (y = 0; y < input->height; ++y) {
+        for (x = 0; x < input->width; ++x) {
+            if (!memcmp(input_data + bpp * x, output_data + bpp * x, bpp))
+                continue;
+
+            if (x < leftmost_x)
+                leftmost_x = x;
+            if (x >= rightmost_x)
+                rightmost_x = x + 1;
+            if (y < topmost_y)
+                topmost_y = y;
+            if (y >= bottommost_y)
+                bottommost_y = y + 1;
+        }
+
+        input_data += input_linesize;
+        output_data += output_linesize;
+    }
+
+    if (leftmost_x == input->width && rightmost_x == 0) {
+        // Empty frame
+        // APNG does not support empty frames, so we make it a 1x1 frame
+        leftmost_x = topmost_y = 0;
+        rightmost_x = bottommost_y = 1;
+    }
+
+    // Do actual inverse blending
+    if (fctl_chunk->blend_op == APNG_BLEND_OP_SOURCE) {
+        output_data = output->data[0];
+        for (y = topmost_y; y < bottommost_y; ++y) {
+            memcpy(output_data,
+                   input->data[0] + input_linesize * y + bpp * leftmost_x,
+                   bpp * (rightmost_x - leftmost_x));
+            output_data += output_linesize;
+        }
+    } else { // APNG_BLEND_OP_OVER
+        size_t transparent_palette_index;
+        uint32_t *palette;
+
+        switch (input->format) {
+        case AV_PIX_FMT_RGBA64BE:
+        case AV_PIX_FMT_YA16BE:
+        case AV_PIX_FMT_RGBA:
+        case AV_PIX_FMT_GRAY8A:
+            break;
+
+        case AV_PIX_FMT_PAL8:
+            palette = (uint32_t*)input->data[1];
+            for (transparent_palette_index = 0; transparent_palette_index < 256; ++transparent_palette_index)
+                if (palette[transparent_palette_index] >> 24 == 0)
+                    break;
+            break;
+
+        default:
+            // No alpha, so blending not possible
+            return -1;
+        }
+
+        for (y = topmost_y; y < bottommost_y; ++y) {
+            uint8_t *foreground = input->data[0] + input_linesize * y + bpp * leftmost_x;
+            uint8_t *background = output->data[0] + output_linesize * y + bpp * leftmost_x;
+            output_data = output->data[0] + output_linesize * (y - topmost_y);
+            for (x = leftmost_x; x < rightmost_x; ++x, foreground += bpp, background += bpp, output_data += bpp) {
+                if (!memcmp(foreground, background, bpp)) {
+                    if (input->format == AV_PIX_FMT_PAL8) {
+                        if (transparent_palette_index == 256) {
+                            // Need fully transparent colour, but none exists
+                            return -1;
+                        }
+
+                        *output_data = transparent_palette_index;
+                    } else {
+                        memset(output_data, 0, bpp);
+                    }
+                    continue;
+                }
+
+                // Check for special alpha values, since full inverse
+                // alpha-on-alpha blending is rarely possible, and when
+                // possible, doesn't compress much better than
+                // APNG_BLEND_OP_SOURCE blending
+                switch (input->format) {
+                case AV_PIX_FMT_RGBA64BE:
+                    if (((uint16_t*)foreground)[3] == 0xffff ||
+                        ((uint16_t*)background)[3] == 0)
+                        break;
+                    return -1;
+
+                case AV_PIX_FMT_YA16BE:
+                    if (((uint16_t*)foreground)[1] == 0xffff ||
+                        ((uint16_t*)background)[1] == 0)
+                        break;
+                    return -1;
+
+                case AV_PIX_FMT_RGBA:
+                    if (foreground[3] == 0xff || background[3] == 0)
+                        break;
+                    return -1;
+
+                case AV_PIX_FMT_GRAY8A:
+                    if (foreground[1] == 0xff || background[1] == 0)
+                        break;
+                    return -1;
+
+                case AV_PIX_FMT_PAL8:
+                    if (palette[*foreground] >> 24 == 0xff ||
+                        palette[*background] >> 24 == 0)
+                        break;
+                    return -1;
+                }
+
+                memmove(output_data, foreground, bpp);
+            }
+        }
+    }
+
+    output->width = rightmost_x - leftmost_x;
+    output->height = bottommost_y - topmost_y;
+    fctl_chunk->width = output->width;
+    fctl_chunk->height = output->height;
+    fctl_chunk->x_offset = leftmost_x;
+    fctl_chunk->y_offset = topmost_y;
+
+    return 0;
+}
+
+static int apng_encode_frame(AVCodecContext *avctx, const AVFrame *pict,
+                             APNGFctlChunk *best_fctl_chunk, APNGFctlChunk *best_last_fctl_chunk)
+{
+    PNGEncContext *s = avctx->priv_data;
+    int ret;
+    unsigned int y;
+    AVFrame* diffFrame;
+    uint8_t bpp = (s->bits_per_pixel + 7) >> 3;
+    uint8_t *original_bytestream, *original_bytestream_end;
+    uint8_t *temp_bytestream = 0, *temp_bytestream_end;
+    uint32_t best_sequence_number;
+    uint8_t *best_bytestream;
+    size_t best_bytestream_size = SIZE_MAX;
+    APNGFctlChunk last_fctl_chunk = *best_last_fctl_chunk;
+    APNGFctlChunk fctl_chunk = *best_fctl_chunk;
+
+    if (avctx->frame_number == 0) {
+        best_fctl_chunk->width = pict->width;
+        best_fctl_chunk->height = pict->height;
+        best_fctl_chunk->x_offset = 0;
+        best_fctl_chunk->y_offset = 0;
+        best_fctl_chunk->blend_op = APNG_BLEND_OP_SOURCE;
+        return encode_frame(avctx, pict);
+    }
+
+    diffFrame = av_frame_alloc();
+    if (!diffFrame)
+        return AVERROR(ENOMEM);
+
+    diffFrame->format = pict->format;
+    diffFrame->width = pict->width;
+    diffFrame->height = pict->height;
+    if ((ret = av_frame_get_buffer(diffFrame, 32)) < 0)
+        goto fail;
+
+    original_bytestream = s->bytestream;
+    original_bytestream_end = s->bytestream_end;
+
+    temp_bytestream = av_malloc(original_bytestream_end - original_bytestream);
+    temp_bytestream_end = temp_bytestream + (original_bytestream_end - original_bytestream);
+    if (!temp_bytestream) {
+        ret = AVERROR(ENOMEM);
+        goto fail;
+    }
+
+    for (last_fctl_chunk.dispose_op = 0; last_fctl_chunk.dispose_op < 3; ++last_fctl_chunk.dispose_op) {
+        // 0: APNG_DISPOSE_OP_NONE
+        // 1: APNG_DISPOSE_OP_BACKGROUND
+        // 2: APNG_DISPOSE_OP_PREVIOUS
+
+        for (fctl_chunk.blend_op = 0; fctl_chunk.blend_op < 2; ++fctl_chunk.blend_op) {
+            // 0: APNG_BLEND_OP_SOURCE
+            // 1: APNG_BLEND_OP_OVER
+
+            uint32_t original_sequence_number = s->sequence_number, sequence_number;
+            uint8_t *bytestream_start = s->bytestream;
+            size_t bytestream_size;
+
+            // Do disposal
+            if (last_fctl_chunk.dispose_op != APNG_DISPOSE_OP_PREVIOUS) {
+                diffFrame->width = pict->width;
+                diffFrame->height = pict->height;
+                ret = av_frame_copy(diffFrame, s->last_frame);
+                if (ret < 0)
+                    goto fail;
+
+                if (last_fctl_chunk.dispose_op == APNG_DISPOSE_OP_BACKGROUND) {
+                    for (y = last_fctl_chunk.y_offset; y < last_fctl_chunk.y_offset + last_fctl_chunk.height; ++y) {
+                        size_t row_start = diffFrame->linesize[0] * y + bpp * last_fctl_chunk.x_offset;
+                        memset(diffFrame->data[0] + row_start, 0, bpp * last_fctl_chunk.width);
+                    }
+                }
+            } else {
+                if (!s->prev_frame)
+                    continue;
+
+                diffFrame->width = pict->width;
+                diffFrame->height = pict->height;
+                ret = av_frame_copy(diffFrame, s->prev_frame);
+                if (ret < 0)
+                    goto fail;
+            }
+
+            // Do inverse blending
+            if (apng_do_inverse_blend(diffFrame, pict, &fctl_chunk, bpp) < 0)
+                continue;
+
+            // Do encoding
+            ret = encode_frame(avctx, diffFrame);
+            sequence_number = s->sequence_number;
+            s->sequence_number = original_sequence_number;
+            bytestream_size = s->bytestream - bytestream_start;
+            s->bytestream = bytestream_start;
+            if (ret < 0)
+                goto fail;
+
+            if (bytestream_size < best_bytestream_size) {
+                *best_fctl_chunk = fctl_chunk;
+                *best_last_fctl_chunk = last_fctl_chunk;
+
+                best_sequence_number = sequence_number;
+                best_bytestream = s->bytestream;
+                best_bytestream_size = bytestream_size;
+
+                if (best_bytestream == original_bytestream) {
+                    s->bytestream = temp_bytestream;
+                    s->bytestream_end = temp_bytestream_end;
+                } else {
+                    s->bytestream = original_bytestream;
+                    s->bytestream_end = original_bytestream_end;
+                }
+            }
+        }
+    }
+
+    s->sequence_number = best_sequence_number;
+    s->bytestream = original_bytestream + best_bytestream_size;
+    s->bytestream_end = original_bytestream_end;
+    if (best_bytestream != original_bytestream)
+        memcpy(original_bytestream, best_bytestream, best_bytestream_size);
+
+    ret = 0;
+
+fail:
+    av_freep(&temp_bytestream);
+    av_frame_free(&diffFrame);
     return ret;
- fail:
-    ret = -1;
-    goto the_end;
 }
 
-static av_cold int png_enc_init(AVCodecContext *avctx){
+static int encode_apng(AVCodecContext *avctx, AVPacket *pkt,
+                       const AVFrame *pict, int *got_packet)
+{
+    PNGEncContext *s = avctx->priv_data;
+    int ret;
+    int enc_row_size;
+    size_t max_packet_size;
+    APNGFctlChunk fctl_chunk = {0};
+
+    if (pict && avctx->codec_id == AV_CODEC_ID_APNG && s->color_type == PNG_COLOR_TYPE_PALETTE) {
+        uint32_t checksum = ~av_crc(av_crc_get_table(AV_CRC_32_IEEE_LE), ~0U, pict->data[1], 256 * sizeof(uint32_t));
+
+        if (avctx->frame_number == 0) {
+            s->palette_checksum = checksum;
+        } else if (checksum != s->palette_checksum) {
+            av_log(avctx, AV_LOG_ERROR,
+                   "Input contains more than one unique palette. APNG does not support multiple palettes.\n");
+            return -1;
+        }
+    }
+
+    enc_row_size    = deflateBound(&s->zstream, (avctx->width * s->bits_per_pixel + 7) >> 3);
+    max_packet_size =
+        AV_INPUT_BUFFER_MIN_SIZE + // headers
+        avctx->height * (
+            enc_row_size +
+            (4 + 12) * (((int64_t)enc_row_size + IOBUF_SIZE - 1) / IOBUF_SIZE) // fdAT * ceil(enc_row_size / IOBUF_SIZE)
+        );
+    if (max_packet_size > INT_MAX)
+        return AVERROR(ENOMEM);
+
+    if (avctx->frame_number == 0) {
+        if (!pict)
+            return AVERROR(EINVAL);
+
+        s->bytestream = avctx->extradata = av_malloc(FF_MIN_BUFFER_SIZE);
+        if (!avctx->extradata)
+            return AVERROR(ENOMEM);
+
+        ret = encode_headers(avctx, pict);
+        if (ret < 0)
+            return ret;
+
+        avctx->extradata_size = s->bytestream - avctx->extradata;
+
+        s->last_frame_packet = av_malloc(max_packet_size);
+        if (!s->last_frame_packet)
+            return AVERROR(ENOMEM);
+    } else if (s->last_frame) {
+        ret = ff_alloc_packet2(avctx, pkt, max_packet_size, 0);
+        if (ret < 0)
+            return ret;
+
+        memcpy(pkt->data, s->last_frame_packet, s->last_frame_packet_size);
+        pkt->size = s->last_frame_packet_size;
+        pkt->pts = pkt->dts = s->last_frame->pts;
+    }
+
+    if (pict) {
+        s->bytestream_start =
+        s->bytestream       = s->last_frame_packet;
+        s->bytestream_end   = s->bytestream + max_packet_size;
+
+        // We're encoding the frame first, so we have to do a bit of shuffling around
+        // to have the image data write to the correct place in the buffer
+        fctl_chunk.sequence_number = s->sequence_number;
+        ++s->sequence_number;
+        s->bytestream += 26 + 12;
+
+        ret = apng_encode_frame(avctx, pict, &fctl_chunk, &s->last_frame_fctl);
+        if (ret < 0)
+            return ret;
+
+        fctl_chunk.delay_num = 0; // delay filled in during muxing
+        fctl_chunk.delay_den = 0;
+    } else {
+        s->last_frame_fctl.dispose_op = APNG_DISPOSE_OP_NONE;
+    }
+
+    if (s->last_frame) {
+        uint8_t* last_fctl_chunk_start = pkt->data;
+        uint8_t buf[26];
+
+        AV_WB32(buf + 0, s->last_frame_fctl.sequence_number);
+        AV_WB32(buf + 4, s->last_frame_fctl.width);
+        AV_WB32(buf + 8, s->last_frame_fctl.height);
+        AV_WB32(buf + 12, s->last_frame_fctl.x_offset);
+        AV_WB32(buf + 16, s->last_frame_fctl.y_offset);
+        AV_WB16(buf + 20, s->last_frame_fctl.delay_num);
+        AV_WB16(buf + 22, s->last_frame_fctl.delay_den);
+        buf[24] = s->last_frame_fctl.dispose_op;
+        buf[25] = s->last_frame_fctl.blend_op;
+        png_write_chunk(&last_fctl_chunk_start, MKTAG('f', 'c', 'T', 'L'), buf, 26);
+
+        *got_packet = 1;
+    }
+
+    if (pict) {
+        if (!s->last_frame) {
+            s->last_frame = av_frame_alloc();
+            if (!s->last_frame)
+                return AVERROR(ENOMEM);
+        } else if (s->last_frame_fctl.dispose_op != APNG_DISPOSE_OP_PREVIOUS) {
+            if (!s->prev_frame) {
+                s->prev_frame = av_frame_alloc();
+                if (!s->prev_frame)
+                    return AVERROR(ENOMEM);
+
+                s->prev_frame->format = pict->format;
+                s->prev_frame->width = pict->width;
+                s->prev_frame->height = pict->height;
+                if ((ret = av_frame_get_buffer(s->prev_frame, 32)) < 0)
+                    return ret;
+            }
+
+            // Do disposal, but not blending
+            av_frame_copy(s->prev_frame, s->last_frame);
+            if (s->last_frame_fctl.dispose_op == APNG_DISPOSE_OP_BACKGROUND) {
+                uint32_t y;
+                uint8_t bpp = (s->bits_per_pixel + 7) >> 3;
+                for (y = s->last_frame_fctl.y_offset; y < s->last_frame_fctl.y_offset + s->last_frame_fctl.height; ++y) {
+                    size_t row_start = s->prev_frame->linesize[0] * y + bpp * s->last_frame_fctl.x_offset;
+                    memset(s->prev_frame->data[0] + row_start, 0, bpp * s->last_frame_fctl.width);
+                }
+            }
+        }
+
+        av_frame_unref(s->last_frame);
+        ret = av_frame_ref(s->last_frame, (AVFrame*)pict);
+        if (ret < 0)
+            return ret;
+
+        s->last_frame_fctl = fctl_chunk;
+        s->last_frame_packet_size = s->bytestream - s->bytestream_start;
+    } else {
+        av_frame_free(&s->last_frame);
+    }
+
+    return 0;
+}
+
+static av_cold int png_enc_init(AVCodecContext *avctx)
+{
     PNGEncContext *s = avctx->priv_data;
+    int compression_level;
+
+    switch (avctx->pix_fmt) {
+    case AV_PIX_FMT_RGBA:
+        avctx->bits_per_coded_sample = 32;
+        break;
+    case AV_PIX_FMT_RGB24:
+        avctx->bits_per_coded_sample = 24;
+        break;
+    case AV_PIX_FMT_GRAY8:
+        avctx->bits_per_coded_sample = 0x28;
+        break;
+    case AV_PIX_FMT_MONOBLACK:
+        avctx->bits_per_coded_sample = 1;
+        break;
+    case AV_PIX_FMT_PAL8:
+        avctx->bits_per_coded_sample = 8;
+    }
+
+#if FF_API_CODED_FRAME
+FF_DISABLE_DEPRECATION_WARNINGS
+    avctx->coded_frame->pict_type = AV_PICTURE_TYPE_I;
+    avctx->coded_frame->key_frame = 1;
+FF_ENABLE_DEPRECATION_WARNINGS
+#endif
 
-    avcodec_get_frame_defaults(&s->picture);
-    avctx->coded_frame= &s->picture;
-    ff_dsputil_init(&s->dsp, avctx);
+    ff_huffyuvencdsp_init(&s->hdsp);
 
-    s->filter_type = av_clip(avctx->prediction_method, PNG_FILTER_VALUE_NONE, PNG_FILTER_VALUE_MIXED);
-    if(avctx->pix_fmt == PIX_FMT_MONOBLACK)
+#if FF_API_PRIVATE_OPT
+FF_DISABLE_DEPRECATION_WARNINGS
+    if (avctx->prediction_method)
+        s->filter_type = av_clip(avctx->prediction_method,
+                                 PNG_FILTER_VALUE_NONE,
+                                 PNG_FILTER_VALUE_MIXED);
+FF_ENABLE_DEPRECATION_WARNINGS
+#endif
+
+    if (avctx->pix_fmt == AV_PIX_FMT_MONOBLACK)
         s->filter_type = PNG_FILTER_VALUE_NONE;
 
+    if (s->dpi && s->dpm) {
+      av_log(avctx, AV_LOG_ERROR, "Only one of 'dpi' or 'dpm' options should be set\n");
+      return AVERROR(EINVAL);
+    } else if (s->dpi) {
+      s->dpm = s->dpi * 10000 / 254;
+    }
+
+    s->is_progressive = !!(avctx->flags & AV_CODEC_FLAG_INTERLACED_DCT);
+    switch (avctx->pix_fmt) {
+    case AV_PIX_FMT_RGBA64BE:
+        s->bit_depth = 16;
+        s->color_type = PNG_COLOR_TYPE_RGB_ALPHA;
+        break;
+    case AV_PIX_FMT_RGB48BE:
+        s->bit_depth = 16;
+        s->color_type = PNG_COLOR_TYPE_RGB;
+        break;
+    case AV_PIX_FMT_RGBA:
+        s->bit_depth  = 8;
+        s->color_type = PNG_COLOR_TYPE_RGB_ALPHA;
+        break;
+    case AV_PIX_FMT_RGB24:
+        s->bit_depth  = 8;
+        s->color_type = PNG_COLOR_TYPE_RGB;
+        break;
+    case AV_PIX_FMT_GRAY16BE:
+        s->bit_depth  = 16;
+        s->color_type = PNG_COLOR_TYPE_GRAY;
+        break;
+    case AV_PIX_FMT_GRAY8:
+        s->bit_depth  = 8;
+        s->color_type = PNG_COLOR_TYPE_GRAY;
+        break;
+    case AV_PIX_FMT_GRAY8A:
+        s->bit_depth = 8;
+        s->color_type = PNG_COLOR_TYPE_GRAY_ALPHA;
+        break;
+    case AV_PIX_FMT_YA16BE:
+        s->bit_depth = 16;
+        s->color_type = PNG_COLOR_TYPE_GRAY_ALPHA;
+        break;
+    case AV_PIX_FMT_MONOBLACK:
+        s->bit_depth  = 1;
+        s->color_type = PNG_COLOR_TYPE_GRAY;
+        break;
+    case AV_PIX_FMT_PAL8:
+        s->bit_depth  = 8;
+        s->color_type = PNG_COLOR_TYPE_PALETTE;
+        break;
+    default:
+        return -1;
+    }
+    s->bits_per_pixel = ff_png_get_nb_channels(s->color_type) * s->bit_depth;
+
+    s->zstream.zalloc = ff_png_zalloc;
+    s->zstream.zfree  = ff_png_zfree;
+    s->zstream.opaque = NULL;
+    compression_level = avctx->compression_level == FF_COMPRESSION_DEFAULT
+                      ? Z_DEFAULT_COMPRESSION
+                      : av_clip(avctx->compression_level, 0, 9);
+    if (deflateInit2(&s->zstream, compression_level, Z_DEFLATED, 15, 8, Z_DEFAULT_STRATEGY) != Z_OK)
+        return -1;
+
+    return 0;
+}
+
+static av_cold int png_enc_close(AVCodecContext *avctx)
+{
+    PNGEncContext *s = avctx->priv_data;
+
+    deflateEnd(&s->zstream);
+    av_frame_free(&s->last_frame);
+    av_frame_free(&s->prev_frame);
+    av_freep(&s->last_frame_packet);
     return 0;
 }
 
+#define OFFSET(x) offsetof(PNGEncContext, x)
+#define VE AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_ENCODING_PARAM
+static const AVOption options[] = {
+    {"dpi", "Set image resolution (in dots per inch)",  OFFSET(dpi), AV_OPT_TYPE_INT, {.i64 = 0}, 0, 0x10000, VE},
+    {"dpm", "Set image resolution (in dots per meter)", OFFSET(dpm), AV_OPT_TYPE_INT, {.i64 = 0}, 0, 0x10000, VE},
+    { "pred", "Prediction method", OFFSET(filter_type), AV_OPT_TYPE_INT, { .i64 = PNG_FILTER_VALUE_NONE }, PNG_FILTER_VALUE_NONE, PNG_FILTER_VALUE_MIXED, VE, "pred" },
+        { "none",  NULL, 0, AV_OPT_TYPE_CONST, { .i64 = PNG_FILTER_VALUE_NONE },  INT_MIN, INT_MAX, VE, "pred" },
+        { "sub",   NULL, 0, AV_OPT_TYPE_CONST, { .i64 = PNG_FILTER_VALUE_SUB },   INT_MIN, INT_MAX, VE, "pred" },
+        { "up",    NULL, 0, AV_OPT_TYPE_CONST, { .i64 = PNG_FILTER_VALUE_UP },    INT_MIN, INT_MAX, VE, "pred" },
+        { "avg",   NULL, 0, AV_OPT_TYPE_CONST, { .i64 = PNG_FILTER_VALUE_AVG },   INT_MIN, INT_MAX, VE, "pred" },
+        { "paeth", NULL, 0, AV_OPT_TYPE_CONST, { .i64 = PNG_FILTER_VALUE_PAETH }, INT_MIN, INT_MAX, VE, "pred" },
+        { "mixed", NULL, 0, AV_OPT_TYPE_CONST, { .i64 = PNG_FILTER_VALUE_MIXED }, INT_MIN, INT_MAX, VE, "pred" },
+    { NULL},
+};
+
+static const AVClass pngenc_class = {
+    .class_name = "PNG encoder",
+    .item_name  = av_default_item_name,
+    .option     = options,
+    .version    = LIBAVUTIL_VERSION_INT,
+};
+
+static const AVClass apngenc_class = {
+    .class_name = "APNG encoder",
+    .item_name  = av_default_item_name,
+    .option     = options,
+    .version    = LIBAVUTIL_VERSION_INT,
+};
+
 AVCodec ff_png_encoder = {
     .name           = "png",
+    .long_name      = NULL_IF_CONFIG_SMALL("PNG (Portable Network Graphics) image"),
     .type           = AVMEDIA_TYPE_VIDEO,
-    .id             = CODEC_ID_PNG,
+    .id             = AV_CODEC_ID_PNG,
     .priv_data_size = sizeof(PNGEncContext),
     .init           = png_enc_init,
-    .encode2        = encode_frame,
-    .pix_fmts       = (const enum PixelFormat[]){
-        PIX_FMT_RGB24, PIX_FMT_RGBA,
-        PIX_FMT_RGB48BE, PIX_FMT_RGBA64BE,
-        PIX_FMT_PAL8,
-        PIX_FMT_GRAY8, PIX_FMT_GRAY8A,
-        PIX_FMT_GRAY16BE,
-        PIX_FMT_MONOBLACK, PIX_FMT_NONE
+    .close          = png_enc_close,
+    .encode2        = encode_png,
+    .capabilities   = AV_CODEC_CAP_FRAME_THREADS | AV_CODEC_CAP_INTRA_ONLY,
+    .pix_fmts       = (const enum AVPixelFormat[]) {
+        AV_PIX_FMT_RGB24, AV_PIX_FMT_RGBA,
+        AV_PIX_FMT_RGB48BE, AV_PIX_FMT_RGBA64BE,
+        AV_PIX_FMT_PAL8,
+        AV_PIX_FMT_GRAY8, AV_PIX_FMT_GRAY8A,
+        AV_PIX_FMT_GRAY16BE, AV_PIX_FMT_YA16BE,
+        AV_PIX_FMT_MONOBLACK, AV_PIX_FMT_NONE
     },
-    .long_name      = NULL_IF_CONFIG_SMALL("PNG (Portable Network Graphics) image"),
+    .priv_class     = &pngenc_class,
+};
+
+AVCodec ff_apng_encoder = {
+    .name           = "apng",
+    .long_name      = NULL_IF_CONFIG_SMALL("APNG (Animated Portable Network Graphics) image"),
+    .type           = AVMEDIA_TYPE_VIDEO,
+    .id             = AV_CODEC_ID_APNG,
+    .priv_data_size = sizeof(PNGEncContext),
+    .init           = png_enc_init,
+    .close          = png_enc_close,
+    .encode2        = encode_apng,
+    .capabilities   = CODEC_CAP_DELAY,
+    .pix_fmts       = (const enum AVPixelFormat[]) {
+        AV_PIX_FMT_RGB24, AV_PIX_FMT_RGBA,
+        AV_PIX_FMT_RGB48BE, AV_PIX_FMT_RGBA64BE,
+        AV_PIX_FMT_PAL8,
+        AV_PIX_FMT_GRAY8, AV_PIX_FMT_GRAY8A,
+        AV_PIX_FMT_GRAY16BE, AV_PIX_FMT_YA16BE,
+        AV_PIX_FMT_MONOBLACK, AV_PIX_FMT_NONE
+    },
+    .priv_class     = &apngenc_class,
 };