Merge commit 'df6737a55f5dc7c0ae5272bc5fa6182836d5481c'
[ffmpeg.git] / libavresample / utils.c
1 /*
2  * Copyright (c) 2012 Justin Ruggles <justin.ruggles@gmail.com>
3  *
4  * This file is part of FFmpeg.
5  *
6  * FFmpeg is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License as published by the Free Software Foundation; either
9  * version 2.1 of the License, or (at your option) any later version.
10  *
11  * FFmpeg is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with FFmpeg; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20
21 #include "libavutil/common.h"
22 #include "libavutil/dict.h"
23 // #include "libavutil/error.h"
24 #include "libavutil/log.h"
25 #include "libavutil/mem.h"
26 #include "libavutil/opt.h"
27
28 #include "avresample.h"
29 #include "internal.h"
30 #include "audio_data.h"
31 #include "audio_convert.h"
32 #include "audio_mix.h"
33 #include "resample.h"
34
35 int avresample_open(AVAudioResampleContext *avr)
36 {
37     int ret;
38
39     /* set channel mixing parameters */
40     avr->in_channels = av_get_channel_layout_nb_channels(avr->in_channel_layout);
41     if (avr->in_channels <= 0 || avr->in_channels > AVRESAMPLE_MAX_CHANNELS) {
42         av_log(avr, AV_LOG_ERROR, "Invalid input channel layout: %"PRIu64"\n",
43                avr->in_channel_layout);
44         return AVERROR(EINVAL);
45     }
46     avr->out_channels = av_get_channel_layout_nb_channels(avr->out_channel_layout);
47     if (avr->out_channels <= 0 || avr->out_channels > AVRESAMPLE_MAX_CHANNELS) {
48         av_log(avr, AV_LOG_ERROR, "Invalid output channel layout: %"PRIu64"\n",
49                avr->out_channel_layout);
50         return AVERROR(EINVAL);
51     }
52     avr->resample_channels = FFMIN(avr->in_channels, avr->out_channels);
53     avr->downmix_needed    = avr->in_channels  > avr->out_channels;
54     avr->upmix_needed      = avr->out_channels > avr->in_channels ||
55                              (!avr->downmix_needed && (avr->mix_matrix ||
56                               avr->in_channel_layout != avr->out_channel_layout));
57     avr->mixing_needed     = avr->downmix_needed || avr->upmix_needed;
58
59     /* set resampling parameters */
60     avr->resample_needed   = avr->in_sample_rate != avr->out_sample_rate ||
61                              avr->force_resampling;
62
63     /* select internal sample format if not specified by the user */
64     if (avr->internal_sample_fmt == AV_SAMPLE_FMT_NONE &&
65         (avr->mixing_needed || avr->resample_needed)) {
66         enum AVSampleFormat  in_fmt = av_get_planar_sample_fmt(avr->in_sample_fmt);
67         enum AVSampleFormat out_fmt = av_get_planar_sample_fmt(avr->out_sample_fmt);
68         int max_bps = FFMAX(av_get_bytes_per_sample(in_fmt),
69                             av_get_bytes_per_sample(out_fmt));
70         if (max_bps <= 2) {
71             avr->internal_sample_fmt = AV_SAMPLE_FMT_S16P;
72         } else if (avr->mixing_needed) {
73             avr->internal_sample_fmt = AV_SAMPLE_FMT_FLTP;
74         } else {
75             if (max_bps <= 4) {
76                 if (in_fmt  == AV_SAMPLE_FMT_S32P ||
77                     out_fmt == AV_SAMPLE_FMT_S32P) {
78                     if (in_fmt  == AV_SAMPLE_FMT_FLTP ||
79                         out_fmt == AV_SAMPLE_FMT_FLTP) {
80                         /* if one is s32 and the other is flt, use dbl */
81                         avr->internal_sample_fmt = AV_SAMPLE_FMT_DBLP;
82                     } else {
83                         /* if one is s32 and the other is s32, s16, or u8, use s32 */
84                         avr->internal_sample_fmt = AV_SAMPLE_FMT_S32P;
85                     }
86                 } else {
87                     /* if one is flt and the other is flt, s16 or u8, use flt */
88                     avr->internal_sample_fmt = AV_SAMPLE_FMT_FLTP;
89                 }
90             } else {
91                 /* if either is dbl, use dbl */
92                 avr->internal_sample_fmt = AV_SAMPLE_FMT_DBLP;
93             }
94         }
95         av_log(avr, AV_LOG_DEBUG, "Using %s as internal sample format\n",
96                av_get_sample_fmt_name(avr->internal_sample_fmt));
97     }
98
99     /* treat all mono as planar for easier comparison */
100     if (avr->in_channels == 1)
101         avr->in_sample_fmt = av_get_planar_sample_fmt(avr->in_sample_fmt);
102     if (avr->out_channels == 1)
103         avr->out_sample_fmt = av_get_planar_sample_fmt(avr->out_sample_fmt);
104
105     /* we may need to add an extra conversion in order to remap channels if
106        the output format is not planar */
107     if (avr->use_channel_map && !avr->mixing_needed && !avr->resample_needed &&
108         !av_sample_fmt_is_planar(avr->out_sample_fmt)) {
109         avr->internal_sample_fmt = av_get_planar_sample_fmt(avr->out_sample_fmt);
110     }
111
112     /* set sample format conversion parameters */
113     if (avr->resample_needed || avr->mixing_needed)
114         avr->in_convert_needed = avr->in_sample_fmt != avr->internal_sample_fmt;
115     else
116         avr->in_convert_needed = avr->use_channel_map &&
117                                  !av_sample_fmt_is_planar(avr->out_sample_fmt);
118
119     if (avr->resample_needed || avr->mixing_needed || avr->in_convert_needed)
120         avr->out_convert_needed = avr->internal_sample_fmt != avr->out_sample_fmt;
121     else
122         avr->out_convert_needed = avr->in_sample_fmt != avr->out_sample_fmt;
123
124     avr->in_copy_needed = !avr->in_convert_needed && (avr->mixing_needed ||
125                           (avr->use_channel_map && avr->resample_needed));
126
127     if (avr->use_channel_map) {
128         if (avr->in_copy_needed) {
129             avr->remap_point = REMAP_IN_COPY;
130             av_dlog(avr, "remap channels during in_copy\n");
131         } else if (avr->in_convert_needed) {
132             avr->remap_point = REMAP_IN_CONVERT;
133             av_dlog(avr, "remap channels during in_convert\n");
134         } else if (avr->out_convert_needed) {
135             avr->remap_point = REMAP_OUT_CONVERT;
136             av_dlog(avr, "remap channels during out_convert\n");
137         } else {
138             avr->remap_point = REMAP_OUT_COPY;
139             av_dlog(avr, "remap channels during out_copy\n");
140         }
141
142 #ifdef DEBUG
143         {
144             int ch;
145             av_dlog(avr, "output map: ");
146             if (avr->ch_map_info.do_remap)
147                 for (ch = 0; ch < avr->in_channels; ch++)
148                     av_dlog(avr, " % 2d", avr->ch_map_info.channel_map[ch]);
149             else
150                 av_dlog(avr, "n/a");
151             av_dlog(avr, "\n");
152             av_dlog(avr, "copy map:   ");
153             if (avr->ch_map_info.do_copy)
154                 for (ch = 0; ch < avr->in_channels; ch++)
155                     av_dlog(avr, " % 2d", avr->ch_map_info.channel_copy[ch]);
156             else
157                 av_dlog(avr, "n/a");
158             av_dlog(avr, "\n");
159             av_dlog(avr, "zero map:   ");
160             if (avr->ch_map_info.do_zero)
161                 for (ch = 0; ch < avr->in_channels; ch++)
162                     av_dlog(avr, " % 2d", avr->ch_map_info.channel_zero[ch]);
163             else
164                 av_dlog(avr, "n/a");
165             av_dlog(avr, "\n");
166             av_dlog(avr, "input map:  ");
167             for (ch = 0; ch < avr->in_channels; ch++)
168                 av_dlog(avr, " % 2d", avr->ch_map_info.input_map[ch]);
169             av_dlog(avr, "\n");
170         }
171 #endif
172     } else
173         avr->remap_point = REMAP_NONE;
174
175     /* allocate buffers */
176     if (avr->in_copy_needed || avr->in_convert_needed) {
177         avr->in_buffer = ff_audio_data_alloc(FFMAX(avr->in_channels, avr->out_channels),
178                                              0, avr->internal_sample_fmt,
179                                              "in_buffer");
180         if (!avr->in_buffer) {
181             ret = AVERROR(EINVAL);
182             goto error;
183         }
184     }
185     if (avr->resample_needed) {
186         avr->resample_out_buffer = ff_audio_data_alloc(avr->out_channels,
187                                                        0, avr->internal_sample_fmt,
188                                                        "resample_out_buffer");
189         if (!avr->resample_out_buffer) {
190             ret = AVERROR(EINVAL);
191             goto error;
192         }
193     }
194     if (avr->out_convert_needed) {
195         avr->out_buffer = ff_audio_data_alloc(avr->out_channels, 0,
196                                               avr->out_sample_fmt, "out_buffer");
197         if (!avr->out_buffer) {
198             ret = AVERROR(EINVAL);
199             goto error;
200         }
201     }
202     avr->out_fifo = av_audio_fifo_alloc(avr->out_sample_fmt, avr->out_channels,
203                                         1024);
204     if (!avr->out_fifo) {
205         ret = AVERROR(ENOMEM);
206         goto error;
207     }
208
209     /* setup contexts */
210     if (avr->in_convert_needed) {
211         avr->ac_in = ff_audio_convert_alloc(avr, avr->internal_sample_fmt,
212                                             avr->in_sample_fmt, avr->in_channels,
213                                             avr->in_sample_rate,
214                                             avr->remap_point == REMAP_IN_CONVERT);
215         if (!avr->ac_in) {
216             ret = AVERROR(ENOMEM);
217             goto error;
218         }
219     }
220     if (avr->out_convert_needed) {
221         enum AVSampleFormat src_fmt;
222         if (avr->in_convert_needed)
223             src_fmt = avr->internal_sample_fmt;
224         else
225             src_fmt = avr->in_sample_fmt;
226         avr->ac_out = ff_audio_convert_alloc(avr, avr->out_sample_fmt, src_fmt,
227                                              avr->out_channels,
228                                              avr->out_sample_rate,
229                                              avr->remap_point == REMAP_OUT_CONVERT);
230         if (!avr->ac_out) {
231             ret = AVERROR(ENOMEM);
232             goto error;
233         }
234     }
235     if (avr->resample_needed) {
236         avr->resample = ff_audio_resample_init(avr);
237         if (!avr->resample) {
238             ret = AVERROR(ENOMEM);
239             goto error;
240         }
241     }
242     if (avr->mixing_needed) {
243         avr->am = ff_audio_mix_alloc(avr);
244         if (!avr->am) {
245             ret = AVERROR(ENOMEM);
246             goto error;
247         }
248     }
249
250     return 0;
251
252 error:
253     avresample_close(avr);
254     return ret;
255 }
256
257 void avresample_close(AVAudioResampleContext *avr)
258 {
259     ff_audio_data_free(&avr->in_buffer);
260     ff_audio_data_free(&avr->resample_out_buffer);
261     ff_audio_data_free(&avr->out_buffer);
262     av_audio_fifo_free(avr->out_fifo);
263     avr->out_fifo = NULL;
264     ff_audio_convert_free(&avr->ac_in);
265     ff_audio_convert_free(&avr->ac_out);
266     ff_audio_resample_free(&avr->resample);
267     ff_audio_mix_free(&avr->am);
268     av_freep(&avr->mix_matrix);
269
270     avr->use_channel_map = 0;
271 }
272
273 void avresample_free(AVAudioResampleContext **avr)
274 {
275     if (!*avr)
276         return;
277     avresample_close(*avr);
278     av_opt_free(*avr);
279     av_freep(avr);
280 }
281
282 static int handle_buffered_output(AVAudioResampleContext *avr,
283                                   AudioData *output, AudioData *converted)
284 {
285     int ret;
286
287     if (!output || av_audio_fifo_size(avr->out_fifo) > 0 ||
288         (converted && output->allocated_samples < converted->nb_samples)) {
289         if (converted) {
290             /* if there are any samples in the output FIFO or if the
291                user-supplied output buffer is not large enough for all samples,
292                we add to the output FIFO */
293             av_dlog(avr, "[FIFO] add %s to out_fifo\n", converted->name);
294             ret = ff_audio_data_add_to_fifo(avr->out_fifo, converted, 0,
295                                             converted->nb_samples);
296             if (ret < 0)
297                 return ret;
298         }
299
300         /* if the user specified an output buffer, read samples from the output
301            FIFO to the user output */
302         if (output && output->allocated_samples > 0) {
303             av_dlog(avr, "[FIFO] read from out_fifo to output\n");
304             av_dlog(avr, "[end conversion]\n");
305             return ff_audio_data_read_from_fifo(avr->out_fifo, output,
306                                                 output->allocated_samples);
307         }
308     } else if (converted) {
309         /* copy directly to output if it is large enough or there is not any
310            data in the output FIFO */
311         av_dlog(avr, "[copy] %s to output\n", converted->name);
312         output->nb_samples = 0;
313         ret = ff_audio_data_copy(output, converted,
314                                  avr->remap_point == REMAP_OUT_COPY ?
315                                  &avr->ch_map_info : NULL);
316         if (ret < 0)
317             return ret;
318         av_dlog(avr, "[end conversion]\n");
319         return output->nb_samples;
320     }
321     av_dlog(avr, "[end conversion]\n");
322     return 0;
323 }
324
325 int attribute_align_arg avresample_convert(AVAudioResampleContext *avr,
326                                            uint8_t **output, int out_plane_size,
327                                            int out_samples, uint8_t **input,
328                                            int in_plane_size, int in_samples)
329 {
330     AudioData input_buffer;
331     AudioData output_buffer;
332     AudioData *current_buffer;
333     int ret, direct_output;
334
335     /* reset internal buffers */
336     if (avr->in_buffer) {
337         avr->in_buffer->nb_samples = 0;
338         ff_audio_data_set_channels(avr->in_buffer,
339                                    avr->in_buffer->allocated_channels);
340     }
341     if (avr->resample_out_buffer) {
342         avr->resample_out_buffer->nb_samples = 0;
343         ff_audio_data_set_channels(avr->resample_out_buffer,
344                                    avr->resample_out_buffer->allocated_channels);
345     }
346     if (avr->out_buffer) {
347         avr->out_buffer->nb_samples = 0;
348         ff_audio_data_set_channels(avr->out_buffer,
349                                    avr->out_buffer->allocated_channels);
350     }
351
352     av_dlog(avr, "[start conversion]\n");
353
354     /* initialize output_buffer with output data */
355     direct_output = output && av_audio_fifo_size(avr->out_fifo) == 0;
356     if (output) {
357         ret = ff_audio_data_init(&output_buffer, output, out_plane_size,
358                                  avr->out_channels, out_samples,
359                                  avr->out_sample_fmt, 0, "output");
360         if (ret < 0)
361             return ret;
362         output_buffer.nb_samples = 0;
363     }
364
365     if (input) {
366         /* initialize input_buffer with input data */
367         ret = ff_audio_data_init(&input_buffer, input, in_plane_size,
368                                  avr->in_channels, in_samples,
369                                  avr->in_sample_fmt, 1, "input");
370         if (ret < 0)
371             return ret;
372         current_buffer = &input_buffer;
373
374         if (avr->upmix_needed && !avr->in_convert_needed && !avr->resample_needed &&
375             !avr->out_convert_needed && direct_output && out_samples >= in_samples) {
376             /* in some rare cases we can copy input to output and upmix
377                directly in the output buffer */
378             av_dlog(avr, "[copy] %s to output\n", current_buffer->name);
379             ret = ff_audio_data_copy(&output_buffer, current_buffer,
380                                      avr->remap_point == REMAP_OUT_COPY ?
381                                      &avr->ch_map_info : NULL);
382             if (ret < 0)
383                 return ret;
384             current_buffer = &output_buffer;
385         } else if (avr->remap_point == REMAP_OUT_COPY &&
386                    (!direct_output || out_samples < in_samples)) {
387             /* if remapping channels during output copy, we may need to
388              * use an intermediate buffer in order to remap before adding
389              * samples to the output fifo */
390             av_dlog(avr, "[copy] %s to out_buffer\n", current_buffer->name);
391             ret = ff_audio_data_copy(avr->out_buffer, current_buffer,
392                                      &avr->ch_map_info);
393             if (ret < 0)
394                 return ret;
395             current_buffer = avr->out_buffer;
396         } else if (avr->in_copy_needed || avr->in_convert_needed) {
397             /* if needed, copy or convert input to in_buffer, and downmix if
398                applicable */
399             if (avr->in_convert_needed) {
400                 ret = ff_audio_data_realloc(avr->in_buffer,
401                                             current_buffer->nb_samples);
402                 if (ret < 0)
403                     return ret;
404                 av_dlog(avr, "[convert] %s to in_buffer\n", current_buffer->name);
405                 ret = ff_audio_convert(avr->ac_in, avr->in_buffer,
406                                        current_buffer);
407                 if (ret < 0)
408                     return ret;
409             } else {
410                 av_dlog(avr, "[copy] %s to in_buffer\n", current_buffer->name);
411                 ret = ff_audio_data_copy(avr->in_buffer, current_buffer,
412                                          avr->remap_point == REMAP_IN_COPY ?
413                                          &avr->ch_map_info : NULL);
414                 if (ret < 0)
415                     return ret;
416             }
417             ff_audio_data_set_channels(avr->in_buffer, avr->in_channels);
418             if (avr->downmix_needed) {
419                 av_dlog(avr, "[downmix] in_buffer\n");
420                 ret = ff_audio_mix(avr->am, avr->in_buffer);
421                 if (ret < 0)
422                     return ret;
423             }
424             current_buffer = avr->in_buffer;
425         }
426     } else {
427         /* flush resampling buffer and/or output FIFO if input is NULL */
428         if (!avr->resample_needed)
429             return handle_buffered_output(avr, output ? &output_buffer : NULL,
430                                           NULL);
431         current_buffer = NULL;
432     }
433
434     if (avr->resample_needed) {
435         AudioData *resample_out;
436
437         if (!avr->out_convert_needed && direct_output && out_samples > 0)
438             resample_out = &output_buffer;
439         else
440             resample_out = avr->resample_out_buffer;
441         av_dlog(avr, "[resample] %s to %s\n", current_buffer->name,
442                 resample_out->name);
443         ret = ff_audio_resample(avr->resample, resample_out,
444                                 current_buffer);
445         if (ret < 0)
446             return ret;
447
448         /* if resampling did not produce any samples, just return 0 */
449         if (resample_out->nb_samples == 0) {
450             av_dlog(avr, "[end conversion]\n");
451             return 0;
452         }
453
454         current_buffer = resample_out;
455     }
456
457     if (avr->upmix_needed) {
458         av_dlog(avr, "[upmix] %s\n", current_buffer->name);
459         ret = ff_audio_mix(avr->am, current_buffer);
460         if (ret < 0)
461             return ret;
462     }
463
464     /* if we resampled or upmixed directly to output, return here */
465     if (current_buffer == &output_buffer) {
466         av_dlog(avr, "[end conversion]\n");
467         return current_buffer->nb_samples;
468     }
469
470     if (avr->out_convert_needed) {
471         if (direct_output && out_samples >= current_buffer->nb_samples) {
472             /* convert directly to output */
473             av_dlog(avr, "[convert] %s to output\n", current_buffer->name);
474             ret = ff_audio_convert(avr->ac_out, &output_buffer, current_buffer);
475             if (ret < 0)
476                 return ret;
477
478             av_dlog(avr, "[end conversion]\n");
479             return output_buffer.nb_samples;
480         } else {
481             ret = ff_audio_data_realloc(avr->out_buffer,
482                                         current_buffer->nb_samples);
483             if (ret < 0)
484                 return ret;
485             av_dlog(avr, "[convert] %s to out_buffer\n", current_buffer->name);
486             ret = ff_audio_convert(avr->ac_out, avr->out_buffer,
487                                    current_buffer);
488             if (ret < 0)
489                 return ret;
490             current_buffer = avr->out_buffer;
491         }
492     }
493
494     return handle_buffered_output(avr, output ? &output_buffer : NULL,
495                                   current_buffer);
496 }
497
498 int avresample_get_matrix(AVAudioResampleContext *avr, double *matrix,
499                           int stride)
500 {
501     int in_channels, out_channels, i, o;
502
503     if (avr->am)
504         return ff_audio_mix_get_matrix(avr->am, matrix, stride);
505
506     in_channels  = av_get_channel_layout_nb_channels(avr->in_channel_layout);
507     out_channels = av_get_channel_layout_nb_channels(avr->out_channel_layout);
508
509     if ( in_channels <= 0 ||  in_channels > AVRESAMPLE_MAX_CHANNELS ||
510         out_channels <= 0 || out_channels > AVRESAMPLE_MAX_CHANNELS) {
511         av_log(avr, AV_LOG_ERROR, "Invalid channel layouts\n");
512         return AVERROR(EINVAL);
513     }
514
515     if (!avr->mix_matrix) {
516         av_log(avr, AV_LOG_ERROR, "matrix is not set\n");
517         return AVERROR(EINVAL);
518     }
519
520     for (o = 0; o < out_channels; o++)
521         for (i = 0; i < in_channels; i++)
522             matrix[o * stride + i] = avr->mix_matrix[o * in_channels + i];
523
524     return 0;
525 }
526
527 int avresample_set_matrix(AVAudioResampleContext *avr, const double *matrix,
528                           int stride)
529 {
530     int in_channels, out_channels, i, o;
531
532     if (avr->am)
533         return ff_audio_mix_set_matrix(avr->am, matrix, stride);
534
535     in_channels  = av_get_channel_layout_nb_channels(avr->in_channel_layout);
536     out_channels = av_get_channel_layout_nb_channels(avr->out_channel_layout);
537
538     if ( in_channels <= 0 ||  in_channels > AVRESAMPLE_MAX_CHANNELS ||
539         out_channels <= 0 || out_channels > AVRESAMPLE_MAX_CHANNELS) {
540         av_log(avr, AV_LOG_ERROR, "Invalid channel layouts\n");
541         return AVERROR(EINVAL);
542     }
543
544     if (avr->mix_matrix)
545         av_freep(&avr->mix_matrix);
546     avr->mix_matrix = av_malloc(in_channels * out_channels *
547                                 sizeof(*avr->mix_matrix));
548     if (!avr->mix_matrix)
549         return AVERROR(ENOMEM);
550
551     for (o = 0; o < out_channels; o++)
552         for (i = 0; i < in_channels; i++)
553             avr->mix_matrix[o * in_channels + i] = matrix[o * stride + i];
554
555     return 0;
556 }
557
558 int avresample_set_channel_mapping(AVAudioResampleContext *avr,
559                                    const int *channel_map)
560 {
561     ChannelMapInfo *info = &avr->ch_map_info;
562     int in_channels, ch, i;
563
564     in_channels = av_get_channel_layout_nb_channels(avr->in_channel_layout);
565     if (in_channels <= 0 ||  in_channels > AVRESAMPLE_MAX_CHANNELS) {
566         av_log(avr, AV_LOG_ERROR, "Invalid input channel layout\n");
567         return AVERROR(EINVAL);
568     }
569
570     memset(info, 0, sizeof(*info));
571     memset(info->input_map, -1, sizeof(info->input_map));
572
573     for (ch = 0; ch < in_channels; ch++) {
574         if (channel_map[ch] >= in_channels) {
575             av_log(avr, AV_LOG_ERROR, "Invalid channel map\n");
576             return AVERROR(EINVAL);
577         }
578         if (channel_map[ch] < 0) {
579             info->channel_zero[ch] =  1;
580             info->channel_map[ch]  = -1;
581             info->do_zero          =  1;
582         } else if (info->input_map[channel_map[ch]] >= 0) {
583             info->channel_copy[ch] = info->input_map[channel_map[ch]];
584             info->channel_map[ch]  = -1;
585             info->do_copy          =  1;
586         } else {
587             info->channel_map[ch]            = channel_map[ch];
588             info->input_map[channel_map[ch]] = ch;
589             info->do_remap                   =  1;
590         }
591     }
592     /* Fill-in unmapped input channels with unmapped output channels.
593        This is used when remapping during conversion from interleaved to
594        planar format. */
595     for (ch = 0, i = 0; ch < in_channels && i < in_channels; ch++, i++) {
596         while (ch < in_channels && info->input_map[ch] >= 0)
597             ch++;
598         while (i < in_channels && info->channel_map[i] >= 0)
599             i++;
600         if (ch >= in_channels || i >= in_channels)
601             break;
602         info->input_map[ch] = i;
603     }
604
605     avr->use_channel_map = 1;
606     return 0;
607 }
608
609 int avresample_available(AVAudioResampleContext *avr)
610 {
611     return av_audio_fifo_size(avr->out_fifo);
612 }
613
614 int avresample_read(AVAudioResampleContext *avr, uint8_t **output, int nb_samples)
615 {
616     if (!output)
617         return av_audio_fifo_drain(avr->out_fifo, nb_samples);
618     return av_audio_fifo_read(avr->out_fifo, (void**)output, nb_samples);
619 }
620
621 unsigned avresample_version(void)
622 {
623     return LIBAVRESAMPLE_VERSION_INT;
624 }
625
626 const char *avresample_license(void)
627 {
628 #define LICENSE_PREFIX "libavresample license: "
629     return LICENSE_PREFIX FFMPEG_LICENSE + sizeof(LICENSE_PREFIX) - 1;
630 }
631
632 const char *avresample_configuration(void)
633 {
634     return FFMPEG_CONFIGURATION;
635 }