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add support for files where the frames do not have a length prefix

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Originally committed as revision 26265 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Sascha Sommer 2011-01-08 15:32:31 +00:00
parent 2a81f4bde5
commit 8b5a780e73
1 changed files with 23 additions and 7 deletions
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30
libavcodec/wmaprodec.c
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@ -300,11 +300,6 @@ static av_cold int decode_init(AVCodecContext *avctx)
s->packet_loss = 1;
s->len_prefix = (s->decode_flags & 0x40);
if (!s->len_prefix) {
av_log_ask_for_sample(avctx, "no length prefix\n");
return AVERROR_INVALIDDATA;
}
/** get frame len */
s->samples_per_frame = 1 << ff_wma_get_frame_len_bits(avctx->sample_rate,
3, s->decode_flags);
@ -1368,6 +1363,7 @@ static int decode_frame(WMAProDecodeCtx *s)
} else
s->samples += s->num_channels * s->samples_per_frame;
if (s->len_prefix) {
if (len != (get_bits_count(gb) - s->frame_offset) + 2) {
/** FIXME: not sure if this is always an error */
av_log(s->avctx, AV_LOG_ERROR, "frame[%i] would have to skip %i bits\n",
@ -1378,6 +1374,10 @@ static int decode_frame(WMAProDecodeCtx *s)
/** skip the rest of the frame data */
skip_bits_long(gb, len - (get_bits_count(gb) - s->frame_offset) - 1);
} else {
while (get_bits_count(gb) < s->num_saved_bits && get_bits1(gb) == 0) {
}
}
/** decode trailer bit */
more_frames = get_bits1(gb);
@ -1515,18 +1515,34 @@ static int decode_packet(AVCodecContext *avctx,
s->num_saved_bits - s->frame_offset);
}
s->packet_loss = 0;
if (s->packet_loss) {
/** reset number of saved bits so that the decoder
does not start to decode incomplete frames in the
s->len_prefix == 0 case */
s->num_saved_bits = 0;
s->packet_loss = 0;
}
} else {
int frame_size;
s->buf_bit_size = avpkt->size << 3;
init_get_bits(gb, avpkt->data, s->buf_bit_size);
skip_bits(gb, s->packet_offset);
if (remaining_bits(s, gb) > s->log2_frame_size &&
if (s->len_prefix && remaining_bits(s, gb) > s->log2_frame_size &&
(frame_size = show_bits(gb, s->log2_frame_size)) &&
frame_size <= remaining_bits(s, gb)) {
save_bits(s, gb, frame_size, 0);
s->packet_done = !decode_frame(s);
} else if (!s->len_prefix
&& s->num_saved_bits > get_bits_count(&s->gb)) {
/** when the frames do not have a length prefix, we don't know
the compressed length of the individual frames
however, we know what part of a new packet belongs to the
previous frame
therefore we save the incoming packet first, then we append
the "previous frame" data from the next packet so that
we get a buffer that only contains full frames */
s->packet_done = !decode_frame(s);
} else
s->packet_done = 1;
}