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alacenc: only encode frame size in header for a final smaller frame 

Otherwise it is not needed because it matches the frame size as encoded in
the extradata.
This commit is contained in:
Justin Ruggles 2012-02-03 17:27:31 -05:00
parent ba821b098b
commit b590f3a7bf
2 changed files with 12 additions and 5 deletions
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13
libavcodec/alacenc.c
View File

@ -120,12 +120,18 @@ static void encode_scalar(AlacEncodeContext *s, int x,
static void write_frame_header(AlacEncodeContext *s, int is_verbatim)
{
int encode_fs = 0;
if (s->frame_size < DEFAULT_FRAME_SIZE)
encode_fs = 1;
put_bits(&s->pbctx, 3, s->avctx->channels-1); // No. of channels -1
put_bits(&s->pbctx, 16, 0); // Seems to be zero
put_bits(&s->pbctx, 1, 1); // Sample count is in the header
put_bits(&s->pbctx, 1, encode_fs); // Sample count is in the header
put_bits(&s->pbctx, 2, 0); // FIXME: Wasted bytes field
put_bits(&s->pbctx, 1, is_verbatim); // Audio block is verbatim
put_bits32(&s->pbctx, s->frame_size); // No. of samples in the frame
if (encode_fs)
put_bits32(&s->pbctx, s->frame_size); // No. of samples in the frame
}
static void calc_predictor_params(AlacEncodeContext *s, int ch)
@ -380,7 +386,8 @@ static void write_compressed_frame(AlacEncodeContext *s)
static av_always_inline int get_max_frame_size(int frame_size, int ch, int bps)
{
return FFALIGN(55 + bps * ch * frame_size + 3, 8) / 8;
int header_bits = 23 + 32 * (frame_size < DEFAULT_FRAME_SIZE);
return FFALIGN(header_bits + bps * ch * frame_size + 3, 8) / 8;
}
static av_cold int alac_encode_close(AVCodecContext *avctx)

4
tests/ref/acodec/alac
View File

@ -1,4 +1,4 @@
db1806d9ffd85c168c2c71a28e6d9229 *./tests/data/acodec/alac.m4a
389410 ./tests/data/acodec/alac.m4a
b9e78aa8b8774a63d187380a47201a37 *./tests/data/acodec/alac.m4a
389154 ./tests/data/acodec/alac.m4a
64151e4bcc2b717aa5a8454d424d6a1f *./tests/data/alac.acodec.out.wav
stddev: 0.00 PSNR:999.99 MAXDIFF: 0 bytes: 1058400/ 1058400