[FFmpeg-devel] CNG (consistent noise generation) patch for AC-3 decoder

[Jonathan Campbell]

On 09/01/2016 07:13 PM, Michael Niedermayer wrote:
> On Thu, Sep 01, 2016 at 06:59:46PM -0700, Jonathan Campbell wrote:
>> I finished the consistent noise generation patch for AC-3 decoding.
>>
>> Set AVOption "cons_noisegen" to 1 (true) to enable it.
>>
>> Git repository:
>> https://github.com/joncampbell123/FFmpeg.git
>>
>> commit dbd086586f0ad1591ea2013293bbb6e4dbfd0455
>> Author: Jonathan Campbell <jonathan at castus.tv>
>> Date:   Thu Sep 1 18:46:16 2016 -0700
>>
>>      AC-3 consistent noise generation: avopt -cons_noisegen <number>
>>
>>      When -cons_noisegen 1, the linear feedback generator used for AC-3
>>      dithering is seeded with the contents of the AC-3 frame. Seeding from
>>      the AC-3 frame ensures the dithering noise comes out exactly the same
>>      when given the same AC-3 frame data, which can then be used by
>>      non-linear editing software to reliably decode discontinuous
>> segments of
>>      an AC-3 bitstream without gaps or discontinuities.
>>
>> Jonathan Campbell
>>
>> Patch follows, hope Thunderbird doesn't garble it:
>>
>> diff --git a/libavcodec/ac3dec.c b/libavcodec/ac3dec.c
>> index fac189b..28048d7 100644
>> --- a/libavcodec/ac3dec.c
>> +++ b/libavcodec/ac3dec.c
>> @@ -1419,6 +1419,19 @@ 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));
> patch looks newline garbled
>
> [...]
>
>
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Yeah, figured that would happen.

Can you accept patches directly from Github?

https://github.com/joncampbell123/FFmpeg/commit/dbd086586f0ad1591ea2013293bbb6e4dbfd0455.patch

Jonathan Campbell