+ mp3->frames_offset = avio_tell(s->pb);
+ mp3->size = c.frame_size;
+ mp3->want=1;
+ mp3->seen=0;
+ mp3->pos=0;
+
+ avio_wb32(s->pb, 0); // frames
+ avio_wb32(s->pb, 0); // size
+
+ // toc
+ for (i = 0; i < VBR_TOC_SIZE; ++i)
+ avio_w8(s->pb, (uint8_t)(255 * i / VBR_TOC_SIZE));
+
+ ffio_fill(s->pb, 0, c.frame_size - needed);
+ avio_flush(s->pb);
+
+ return 0;
+}
+
+/*
+ * Add a frame to XING data.
+ * Following lame's "VbrTag.c".
+ */
+static void mp3_xing_add_frame(AVFormatContext *s, AVPacket *pkt)
+{
+ MP3Context *mp3 = s->priv_data;
+ int i;
+
+ ++mp3->frames;
+ mp3->size += pkt->size;
+
+ if (mp3->want == ++mp3->seen) {
+ mp3->bag[mp3->pos] = mp3->size;
+
+ if (VBR_NUM_BAGS == ++mp3->pos) {
+ /* shrink table to half size by throwing away each second bag. */
+ for (i = 1; i < VBR_NUM_BAGS; i += 2)
+ mp3->bag[i >> 1] = mp3->bag[i];
+
+ /* double wanted amount per bag. */
+ mp3->want <<= 1;
+ /* adjust current position to half of table size. */
+ mp3->pos >>= 1;
+ }
+
+ mp3->seen = 0;
+ }
+}
+
+static void mp3_fix_xing(AVFormatContext *s)
+{
+ MP3Context *mp3 = s->priv_data;
+ int i;
+
+ avio_flush(s->pb);
+ avio_seek(s->pb, mp3->frames_offset, SEEK_SET);
+ avio_wb32(s->pb, mp3->frames);
+ avio_wb32(s->pb, mp3->size);
+
+ avio_w8(s->pb, 0); // first toc entry has to be zero.
+
+ for (i = 1; i < VBR_TOC_SIZE; ++i) {
+ int j = i * mp3->pos / VBR_TOC_SIZE;
+ int seek_point = 256LL * mp3->bag[j] / mp3->size;
+ avio_w8(s->pb, FFMIN(seek_point, 255));
+ }
+
+ avio_flush(s->pb);
+ avio_seek(s->pb, 0, SEEK_END);