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examples/decode_audio: use a parser for splitting the input

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Do not rely on the decoder handling this, as it's not guaranteed to
work.
This commit is contained in:
Anton Khirnov 2016-10-19 21:56:22 +02:00
parent f27e262dbd
commit 0946c754d9
1 changed files with 54 additions and 28 deletions
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82
doc/examples/decode_audio.c
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@ -37,14 +37,40 @@
#define AUDIO_INBUF_SIZE 20480 #define AUDIO_INBUF_SIZE 20480
#define AUDIO_REFILL_THRESH 4096 #define AUDIO_REFILL_THRESH 4096
static void decode(AVCodecContext *dec_ctx, AVPacket *pkt, AVFrame *frame,
FILE *outfile)
{
int len, got_frame;
while (pkt->size > 0) {
len = avcodec_decode_audio4(dec_ctx, frame, &got_frame, pkt);
if (len < 0) {
fprintf(stderr, "Error while decoding\n");
exit(1);
}
if (got_frame) {
/* if a frame has been decoded, output it */
int data_size = av_samples_get_buffer_size(NULL, dec_ctx->channels,
frame->nb_samples,
dec_ctx->sample_fmt, 1);
fwrite(frame->data[0], 1, data_size, outfile);
}
pkt->size -= len;
pkt->data += len;
}
}
int main(int argc, char **argv) int main(int argc, char **argv)
{ {
const char *outfilename, *filename; const char *outfilename, *filename;
const AVCodec *codec; const AVCodec *codec;
AVCodecContext *c= NULL; AVCodecContext *c= NULL;
int len; AVCodecParserContext *parser = NULL;
int len, ret;
FILE *f, *outfile; FILE *f, *outfile;
uint8_t inbuf[AUDIO_INBUF_SIZE + AV_INPUT_BUFFER_PADDING_SIZE]; uint8_t inbuf[AUDIO_INBUF_SIZE + AV_INPUT_BUFFER_PADDING_SIZE];
uint8_t *data;
size_t data_size;
AVPacket avpkt; AVPacket avpkt;
AVFrame *decoded_frame = NULL; AVFrame *decoded_frame = NULL;
@ -67,6 +93,12 @@ int main(int argc, char **argv)
exit(1); exit(1);
} }
parser = av_parser_init(codec->id);
if (!parser) {
fprintf(stderr, "parser not found\n");
exit(1);
}
c = avcodec_alloc_context3(codec); c = avcodec_alloc_context3(codec);
/* open it */ /* open it */
@ -87,12 +119,10 @@ int main(int argc, char **argv)
} }
/* decode until eof */ /* decode until eof */
avpkt.data = inbuf; data = inbuf;
avpkt.size = fread(inbuf, 1, AUDIO_INBUF_SIZE, f); data_size = fread(inbuf, 1, AUDIO_INBUF_SIZE, f);
while (avpkt.size > 0) {
int got_frame = 0;
while (data_size > 0) {
if (!decoded_frame) { if (!decoded_frame) {
if (!(decoded_frame = av_frame_alloc())) { if (!(decoded_frame = av_frame_alloc())) {
fprintf(stderr, "out of memory\n"); fprintf(stderr, "out of memory\n");
@ -100,31 +130,26 @@ int main(int argc, char **argv)
} }
} }
len = avcodec_decode_audio4(c, decoded_frame, &got_frame, &avpkt); ret = av_parser_parse2(parser, c, &avpkt.data, &avpkt.size,
if (len < 0) { data, data_size,
fprintf(stderr, "Error while decoding\n"); AV_NOPTS_VALUE, AV_NOPTS_VALUE, 0);
if (ret < 0) {
fprintf(stderr, "Error while parsing\n");
exit(1); exit(1);
} }
if (got_frame) { data += ret;
/* if a frame has been decoded, output it */ data_size -= ret;
int data_size = av_samples_get_buffer_size(NULL, c->channels,
decoded_frame->nb_samples, if (avpkt.size)
c->sample_fmt, 1); decode(c, &avpkt, decoded_frame, outfile);
fwrite(decoded_frame->data[0], 1, data_size, outfile);
} if (data_size < AUDIO_REFILL_THRESH) {
avpkt.size -= len; memmove(inbuf, data, data_size);
avpkt.data += len; data = inbuf;
if (avpkt.size < AUDIO_REFILL_THRESH) { len = fread(data + data_size, 1,
/* Refill the input buffer, to avoid trying to decode AUDIO_INBUF_SIZE - data_size, f);
* incomplete frames. Instead of this, one could also use
* a parser, or use a proper container format through
* libavformat. */
memmove(inbuf, avpkt.data, avpkt.size);
avpkt.data = inbuf;
len = fread(avpkt.data + avpkt.size, 1,
AUDIO_INBUF_SIZE - avpkt.size, f);
if (len > 0) if (len > 0)
avpkt.size += len; data_size += len;
} }
} }
@ -132,6 +157,7 @@ int main(int argc, char **argv)
fclose(f); fclose(f);
avcodec_free_context(&c); avcodec_free_context(&c);
av_parser_close(parser);
av_frame_free(&decoded_frame); av_frame_free(&decoded_frame);
return 0; return 0;