Chiebot-Mirror
/
FFmpeg
mirror of https://github.com/FFmpeg/FFmpeg.git
8
0
Fork 0
Code Issues Projects Releases Wiki Activity

stereo decorrelation support by (Justin Ruggles jruggle earthlink net>)

Browse Source 
Originally committed as revision 5528 to svn://svn.ffmpeg.org/ffmpeg/trunk
pull/126/head
Michael Niedermayer 19 years ago
parent 6c35b4dee3
commit f33aa12011
3 changed files with 112 additions and 28 deletions
Whitespace
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
Split View
Diff Options
Show Stats Download Patch File Download Diff File
  1. 132
      libavcodec/flacenc.c
  2. 4
      tests/ffmpeg.regression.ref
  3. 4
      tests/rotozoom.regression.ref

132
libavcodec/flacenc.c
Unescape View File

@ -177,7 +177,12 @@ static int flac_encode_init(AVCodecContext *avctx)
s->blocksize = select_blocksize(s->samplerate);
avctx->frame_size = s->blocksize;
s->max_framesize = 14 + (s->blocksize * s->channels * 2);
/* set maximum encoded frame size in verbatim mode */
if(s->channels == 2) {
s->max_framesize = 14 + ((s->blocksize * 33 + 7) >> 3);
} else {
s->max_framesize = 14 + (s->blocksize * s->channels * 2);
}
streaminfo = av_malloc(FLAC_STREAMINFO_SIZE);
write_streaminfo(s, streaminfo);
@ -192,7 +197,7 @@ static int flac_encode_init(AVCodecContext *avctx)
return 0;
}
static int init_frame(FlacEncodeContext *s)
static void init_frame(FlacEncodeContext *s)
{
int i, ch;
FlacFrame *frame;
@ -221,13 +226,6 @@ static int init_frame(FlacEncodeContext *s)
for(ch=0; ch<s->channels; ch++) {
frame->subframes[ch].obits = 16;
}
if(s->channels == 2) {
frame->ch_mode = FLAC_CHMODE_LEFT_RIGHT;
} else {
frame->ch_mode = FLAC_CHMODE_NOT_STEREO;
}
return 0;
}
/**
@ -246,6 +244,94 @@ static void copy_samples(FlacEncodeContext *s, int16_t *samples)
}
}
static int estimate_stereo_mode(int32_t *left_ch, int32_t *right_ch, int n)
{
int i, best;
int32_t lt, rt;
uint64_t left, right, mid, side;
uint64_t score[4];
/* calculate sum of squares for each channel */
left = right = mid = side = 0;
for(i=2; i<n; i++) {
lt = left_ch[i] - 2*left_ch[i-1] + left_ch[i-2];
rt = right_ch[i] - 2*right_ch[i-1] + right_ch[i-2];
mid += ABS((lt + rt) >> 1);
side += ABS(lt - rt);
left += ABS(lt);
right += ABS(rt);
}
/* calculate score for each mode */
score[0] = left + right;
score[1] = left + side;
score[2] = right + side;
score[3] = mid + side;
/* return mode with lowest score */
best = 0;
for(i=1; i<4; i++) {
if(score[i] < score[best]) {
best = i;
}
}
if(best == 0) {
return FLAC_CHMODE_LEFT_RIGHT;
} else if(best == 1) {
return FLAC_CHMODE_LEFT_SIDE;
} else if(best == 2) {
return FLAC_CHMODE_RIGHT_SIDE;
} else {
return FLAC_CHMODE_MID_SIDE;
}
}
/**
* Perform stereo channel decorrelation
*/
static void channel_decorrelation(FlacEncodeContext *ctx)
{
FlacFrame *frame;
int32_t *left, *right;
int i, n;
frame = &ctx->frame;
n = frame->blocksize;
left = frame->subframes[0].samples;
right = frame->subframes[1].samples;
if(ctx->channels != 2) {
frame->ch_mode = FLAC_CHMODE_NOT_STEREO;
return;
}
frame->ch_mode = estimate_stereo_mode(left, right, n);
/* perform decorrelation and adjust bits-per-sample */
if(frame->ch_mode == FLAC_CHMODE_LEFT_RIGHT) {
return;
}
if(frame->ch_mode == FLAC_CHMODE_MID_SIDE) {
int32_t tmp;
for(i=0; i<n; i++) {
tmp = left[i];
left[i] = (tmp + right[i]) >> 1;
right[i] = tmp - right[i];
}
frame->subframes[1].obits++;
} else if(frame->ch_mode == FLAC_CHMODE_LEFT_SIDE) {
for(i=0; i<n; i++) {
right[i] = left[i] - right[i];
}
frame->subframes[1].obits++;
} else {
for(i=0; i<n; i++) {
left[i] -= right[i];
}
frame->subframes[0].obits++;
}
}
static void encode_residual_verbatim(FlacEncodeContext *s, int ch)
{
FlacFrame *frame;
@ -359,19 +445,15 @@ output_frame_header(FlacEncodeContext *s)
put_bits(&s->pb, 3, 4); /* bits-per-sample code */
put_bits(&s->pb, 1, 0);
write_utf8(&s->pb, s->frame_count);
if(frame->bs_code[1] > 0) {
if(frame->bs_code[1] < 256) {
put_bits(&s->pb, 8, frame->bs_code[1]);
} else {
put_bits(&s->pb, 16, frame->bs_code[1]);
}
if(frame->bs_code[0] == 6) {
put_bits(&s->pb, 8, frame->bs_code[1]);
} else if(frame->bs_code[0] == 7) {
put_bits(&s->pb, 16, frame->bs_code[1]);
}
if(s->sr_code[1] > 0) {
if(s->sr_code[1] < 256) {
put_bits(&s->pb, 8, s->sr_code[1]);
} else {
put_bits(&s->pb, 16, s->sr_code[1]);
}
if(s->sr_code[0] == 12) {
put_bits(&s->pb, 8, s->sr_code[1]);
} else if(s->sr_code[0] > 12) {
put_bits(&s->pb, 16, s->sr_code[1]);
}
flush_put_bits(&s->pb);
crc = av_crc(av_crc07, 0, s->pb.buf, put_bits_count(&s->pb)>>3);
@ -493,12 +575,12 @@ static int flac_encode_frame(AVCodecContext *avctx, uint8_t *frame,
s = avctx->priv_data;
s->blocksize = avctx->frame_size;
if(init_frame(s)) {
return 0;
}
init_frame(s);
copy_samples(s, samples);
channel_decorrelation(s);
for(ch=0; ch<s->channels; ch++) {
encode_residual(s, ch);
}
@ -532,6 +614,8 @@ static int flac_encode_frame(AVCodecContext *avctx, uint8_t *frame,
static int flac_encode_close(AVCodecContext *avctx)
{
av_freep(&avctx->extradata);
avctx->extradata_size = 0;
av_freep(&avctx->coded_frame);
return 0;
}

4
tests/ffmpeg.regression.ref
Unescape View File

@ -176,7 +176,7 @@ stddev:1050.18 PSNR:35.89 bytes:1054720
264236 ./data/a-adpcm_yam.wav
e92cec8c07913ffb91ad2b11f79cdc00 *./data/out.wav
stddev:18312.68 PSNR:11.06 bytes:1056768
7bcc7daf968fc489c9b4b7aca5ae380d *./data/a-flac.flac
799336 ./data/a-flac.flac
9ed4957501a56ce9d4e6a6611553a45f *./data/a-flac.flac
801577 ./data/a-flac.flac
0116cdcefd0aeae3ab8e5140c19c725d *./data/out.wav
stddev: 51.59 PSNR:62.07 bytes:1032192

4
tests/rotozoom.regression.ref
Unescape View File

@ -176,7 +176,7 @@ stddev:1050.18 PSNR:35.89 bytes:1054720
264236 ./data/a-adpcm_yam.wav
e92cec8c07913ffb91ad2b11f79cdc00 *./data/out.wav
stddev:18312.68 PSNR:11.06 bytes:1056768
7bcc7daf968fc489c9b4b7aca5ae380d *./data/a-flac.flac
799336 ./data/a-flac.flac
9ed4957501a56ce9d4e6a6611553a45f *./data/a-flac.flac
801577 ./data/a-flac.flac
0116cdcefd0aeae3ab8e5140c19c725d *./data/out.wav
stddev: 51.59 PSNR:62.07 bytes:1032192

Write Preview
Loading…
Cancel
Save