[FFmpeg-devel] [PATCH] avcodec/atrac3: Add multichannel joint stereo ATRAC3

[Paul B Mahol]

On 1/30/17, bananaman255 at gmail.com <bananaman255 at gmail.com> wrote:
> From: bnnm <bananaman255 at gmail.com>
>
> Multichannel joint stereo simply interleaves stereo pairs (6ch: 2ch + 2ch +
> 2ch), so each pair is decoded separatedly.
>
> ***
>
> To test my changes, I converted examples to wav with ffmpeg.exe (old and
> new), and compared them to see they are byte-exact.
>
> Regular 2ch files (JS and normal) were straightforward to test.
>
> For multichannel, to check each JS pair is correctly decoded separatedly I
> did:
> - manually demux 6ch.msf into 3 pairs and convert them (2ch_1.wav +
> 2ch_2.wav + 2ch_3.wav)
> - convert the 6ch.msf file to wav (with my changes)
> - manually demux the 6ch.wav into 3 pairs (6ch_d1.wav + 6ch_d2.wav +
> 6ch_d3.wav)
> - compare each pair (ex. 2ch_3.wav vs 6ch_d3.wav): all pairs are byte-exact.
>
> The new code just processes each JS pair separatedly, there are no algorithm
> changes.
> It could be improved a bit but I'm not sure about typical styles.
> I've only seen 6ch .MSF (probably the AT3 spec only supports 2ch audio).
>
> Signed-off-by: bnnm <bananaman255 at gmail.com>
> ---
>  libavcodec/atrac3.c | 160
> ++++++++++++++++++++++++++++++----------------------
>  1 file changed, 91 insertions(+), 69 deletions(-)
>

applied