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libopus: Add channel mapping 2 support in libopusdec 

Enables demuxing of Ambisonics content coded with channel mapping 2

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
This commit is contained in:
Felicia Lim 2017-03-27 16:21:20 -07:00 committed by Michael Niedermayer
parent 6821b693ec
commit c8c995bc1d
1 changed files with 28 additions and 9 deletions
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23
libavcodec/libopusdec.c
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@ -57,8 +57,6 @@ static av_cold int libopus_decode_init(AVCodecContext *avc)
avc->sample_rate = 48000;
avc->sample_fmt = avc->request_sample_fmt == AV_SAMPLE_FMT_FLT ?
AV_SAMPLE_FMT_FLT : AV_SAMPLE_FMT_S16;
avc->channel_layout = avc->channels > 8 ? 0 :
ff_vorbis_channel_layouts[avc->channels - 1];
if (avc->extradata_size >= OPUS_HEAD_SIZE) {
opus->pre_skip = AV_RL16(avc->extradata + 10);
@ -82,6 +80,9 @@ static av_cold int libopus_decode_init(AVCodecContext *avc)
mapping = mapping_arr;
}
if (channel_map == 1) {
avc->channel_layout = avc->channels > 8 ? 0 :
ff_vorbis_channel_layouts[avc->channels - 1];
if (avc->channels > 2 && avc->channels <= 8) {
const uint8_t *vorbis_offset = ff_vorbis_channel_layout_offsets[avc->channels - 1];
int ch;
@ -91,6 +92,24 @@ static av_cold int libopus_decode_init(AVCodecContext *avc)
mapping_arr[ch] = mapping[vorbis_offset[ch]];
mapping = mapping_arr;
}
} else if (channel_map == 2) {
int ambisonic_order = ff_sqrt(avc->channels) - 1;
if (avc->channels != (ambisonic_order + 1) * (ambisonic_order + 1) &&
avc->channels != (ambisonic_order + 1) * (ambisonic_order + 1) + 2) {
av_log(avc, AV_LOG_ERROR,
"Channel mapping 2 is only specified for channel counts"
" which can be written as (n + 1)^2 or (n + 2)^2 + 2"
" for nonnegative integer n\n");
return AVERROR_INVALIDDATA;
}
if (avc->channels > 227) {
av_log(avc, AV_LOG_ERROR, "Too many channels\n");
return AVERROR_INVALIDDATA;
}
avc->channel_layout = 0;
} else {
avc->channel_layout = 0;
}
opus->dec = opus_multistream_decoder_create(avc->sample_rate, avc->channels,
nb_streams, nb_coupled,