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| author | Jonathan Campbell <jonathan@castus.tv> | 2016-09-03 03:34:01 -0700 |
|---|---|---|
| committer | Michael Niedermayer <michael@niedermayer.cc> | 2017-01-22 02:29:16 +0100 |
| commit | d5d474aea53822642f0465825f8a94cb2327e1e6 (patch) | |
| tree | dc60310bade6ffa810181eb0f0ec92dc41241cdf /libavcodec/ac3dec.c | |
| parent | 76c5a69e26afbfdfc5b6f538594ea12efa31fc9a (diff) | |
| download | ffmpeg-d5d474aea53822642f0465825f8a94cb2327e1e6.tar.gz | |
avcodec/ac3dec: add consistent noise generation option.
use av_lfg_init_from_data() to seed AC-3 dithering from the AC-3 frame
data to make it consistent given the same AC-3 frame, if option is set.
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
Diffstat (limited to 'libavcodec/ac3dec.c')
| -rw-r--r-- | libavcodec/ac3dec.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/libavcodec/ac3dec.c b/libavcodec/ac3dec.c index 499971acce..44991600ec 100644 --- a/libavcodec/ac3dec.c +++ b/libavcodec/ac3dec.c @@ -1426,6 +1426,13 @@ static int ac3_decode_frame(AVCodecContext * avctx, void *data, (const uint16_t *) buf, cnt); } else memcpy(s->input_buffer, buf, FFMIN(buf_size, AC3_FRAME_BUFFER_SIZE)); + + /* if consistent noise generation is enabled, seed the linear feedback generator + * with the contents of the AC-3 frame so that the noise is identical across + * decodes given the same AC-3 frame data, for use with non-linear edititing software. */ + if (s->consistent_noise_generation) + av_lfg_init_from_data(&s->dith_state, s->input_buffer, FFMIN(buf_size, AC3_FRAME_BUFFER_SIZE)); + buf = s->input_buffer; /* initialize the GetBitContext with the start of valid AC-3 Frame */ if ((ret = init_get_bits8(&s->gbc, buf, buf_size)) < 0) |