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Remove useless buffering of input data, so that avcodec_decode_audio never 

returns 0 for a valid frame

Patch by Thorsten Jordan (tjordan atay macrosystem otday de)
[FFmpeg-devel] Behaviour of liba52 decoder

Originally committed as revision 11926 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Thorsten Jordan 2008-02-13 14:20:22 +00:00 committed by Robert Swain
parent 6a1f4535f8
commit 95e5323510
1 changed files with 15 additions and 47 deletions
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62
libavcodec/liba52.c
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@ -37,9 +37,6 @@ static const char* liba52name = "liba52.so.0";
* released under the GPL license.
*/
typedef struct AC3DecodeState {
uint8_t inbuf[4096]; /* input buffer */
uint8_t *inbuf_ptr;
int frame_size;
int flags;
int channels;
a52_state_t* state;
@ -114,8 +111,6 @@ static int a52_decode_init(AVCodecContext *avctx)
#endif
s->state = s->a52_init(0); /* later use CPU flags */
s->samples = s->a52_samples(s->state);
s->inbuf_ptr = s->inbuf;
s->frame_size = 0;
/* allow downmixing to stereo or mono */
if (avctx->channels > 0 && avctx->request_channels > 0 &&
@ -150,7 +145,6 @@ static int a52_decode_frame(AVCodecContext *avctx,
uint8_t *buf, int buf_size)
{
AC3DecodeState *s = avctx->priv_data;
uint8_t *buf_ptr;
int flags, i, len;
int sample_rate, bit_rate;
short *out_samples = data;
@ -161,26 +155,19 @@ static int a52_decode_frame(AVCodecContext *avctx,
*data_size= 0;
buf_ptr = buf;
while (buf_size > 0) {
len = s->inbuf_ptr - s->inbuf;
if (s->frame_size == 0) {
/* no header seen : find one. We need at least 7 bytes to parse it */
len = HEADER_SIZE - len;
if (len > buf_size)
len = buf_size;
memcpy(s->inbuf_ptr, buf_ptr, len);
buf_ptr += len;
s->inbuf_ptr += len;
buf_size -= len;
if ((s->inbuf_ptr - s->inbuf) == HEADER_SIZE) {
len = s->a52_syncinfo(s->inbuf, &s->flags, &sample_rate, &bit_rate);
if (buf_size < HEADER_SIZE) {
av_log(avctx, AV_LOG_ERROR, "Error decoding frame, not enough bytes for header\n");
return -1;
}
len = s->a52_syncinfo(buf, &s->flags, &sample_rate, &bit_rate);
if (len == 0) {
/* no sync found : move by one byte (inefficient, but simple!) */
memcpy(s->inbuf, s->inbuf + 1, HEADER_SIZE - 1);
s->inbuf_ptr--;
} else {
s->frame_size = len;
av_log(avctx, AV_LOG_ERROR, "Error decoding frame, no sync byte at begin\n");
return -1;
}
if (buf_size < len) {
av_log(avctx, AV_LOG_ERROR, "Error decoding frame, not enough bytes\n");
return -1;
}
/* update codec info */
avctx->sample_rate = sample_rate;
s->channels = ac3_channels[s->flags & 7];
@ -194,18 +181,6 @@ static int a52_decode_frame(AVCodecContext *avctx,
avctx->channels = s->channels;
}
avctx->bit_rate = bit_rate;
}
}
} else if (len < s->frame_size) {
len = s->frame_size - len;
if (len > buf_size)
len = buf_size;
memcpy(s->inbuf_ptr, buf_ptr, len);
buf_ptr += len;
s->inbuf_ptr += len;
buf_size -= len;
} else {
flags = s->flags;
if (avctx->channels == 1)
flags = A52_MONO;
@ -214,25 +189,18 @@ static int a52_decode_frame(AVCodecContext *avctx,
else
flags |= A52_ADJUST_LEVEL;
level = 1;
if (s->a52_frame(s->state, s->inbuf, &flags, &level, 384)) {
if (s->a52_frame(s->state, buf, &flags, &level, 384)) {
fail:
av_log(avctx, AV_LOG_ERROR, "Error decoding frame\n");
s->inbuf_ptr = s->inbuf;
s->frame_size = 0;
continue;
return -1;
}
for (i = 0; i < 6; i++) {
if (s->a52_block(s->state))
goto fail;
float_to_int(s->samples, out_samples + i * 256 * avctx->channels, avctx->channels);
}
s->inbuf_ptr = s->inbuf;
s->frame_size = 0;
*data_size = 6 * avctx->channels * 256 * sizeof(int16_t);
break;
}
}
return buf_ptr - buf;
return len;
}
static int a52_decode_end(AVCodecContext *avctx)