Re: [libav-devel] [PATCH 19/25] opus: Implement mapping type 2 for Ambisonic support

[Luca Barbato]

On 6/29/17 12:11 AM, Vittorio Giovara wrote:
> Signed-off-by: Vittorio Giovara 
> ---
>  libavcodec/opus.c | 36 
>  1 file changed, 28 insertions(+), 8 deletions(-)
> 
> diff --git a/libavcodec/opus.c b/libavcodec/opus.c
> index 308d104212..6aebb40155 100644
> --- a/libavcodec/opus.c
> +++ b/libavcodec/opus.c
> @@ -347,7 +347,7 @@ av_cold int ff_opus_parse_extradata(AVCodecContext *avctx,
>  streams= 1;
>  stereo_streams = channels - 1;
>  channel_map= default_channel_map;
> -} else if (map_type == 1 || map_type == 255) {
> +} else if (map_type == 1 || map_type == 2 || map_type == 255) {
>  if (extradata_size < 21 + channels) {
>  av_log(avctx, AV_LOG_ERROR, "Invalid extradata size: %d\n",
> extradata_size);
> @@ -363,6 +363,7 @@ av_cold int ff_opus_parse_extradata(AVCodecContext *avctx,
>  return AVERROR_INVALIDDATA;
>  }
>  
> +layout = 0;
>  if (map_type == 1) {
>  if (channels > 8) {
>  av_log(avctx, AV_LOG_ERROR,
> @@ -371,8 +372,24 @@ av_cold int ff_opus_parse_extradata(AVCodecContext 
> *avctx,
>  }
>  layout = ff_vorbis_ch_layouts[channels - 1].u.mask;
>  channel_reorder = channel_reorder_vorbis;
> -} else
> -layout = 0;
> +} else if (map_type == 2) {
> +int ambisonic_order = ff_sqrt(channels) - 1;
> +int idx = (ambisonic_order + 1) * (ambisonic_order + 1);
> +if (channels <= 227 && (channels == idx || channels == idx + 2)) 
> {
> +av_channel_layout_uninit(>ch_layout);
> +avctx->ch_layout.order = AV_CHANNEL_ORDER_AMBISONIC;
> +avctx->ch_layout.nb_channels = channels;
> +
> +/* ACN order, followed by two optional channels of 
> non-diegetic stereo */
> +if (idx != channels)
> +avctx->ch_layout.u.mask = AV_CH_LAYOUT_STEREO;
> +} else {
> +av_log(avctx, AV_LOG_ERROR, "Channel map 2 is only valid for 
> "
> +   "channel counts equal to (n + 1)^2 + 2j for {n,j} >= 
> 0 "
> +   "(max 227 channels).\n");
> +return AVERROR_INVALIDDATA;
> +}
> +}
>  

Seems fine.

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[libav-devel] [PATCH 19/25] opus: Implement mapping type 2 for Ambisonic support

[Vittorio Giovara]

Signed-off-by: Vittorio Giovara 
---
 libavcodec/opus.c | 36 
 1 file changed, 28 insertions(+), 8 deletions(-)

diff --git a/libavcodec/opus.c b/libavcodec/opus.c
index 308d104212..6aebb40155 100644
--- a/libavcodec/opus.c
+++ b/libavcodec/opus.c
@@ -347,7 +347,7 @@ av_cold int ff_opus_parse_extradata(AVCodecContext *avctx,
 streams= 1;
 stereo_streams = channels - 1;
 channel_map= default_channel_map;
-} else if (map_type == 1 || map_type == 255) {
+} else if (map_type == 1 || map_type == 2 || map_type == 255) {
 if (extradata_size < 21 + channels) {
 av_log(avctx, AV_LOG_ERROR, "Invalid extradata size: %d\n",
extradata_size);
@@ -363,6 +363,7 @@ av_cold int ff_opus_parse_extradata(AVCodecContext *avctx,
 return AVERROR_INVALIDDATA;
 }
 
+layout = 0;
 if (map_type == 1) {
 if (channels > 8) {
 av_log(avctx, AV_LOG_ERROR,
@@ -371,8 +372,24 @@ av_cold int ff_opus_parse_extradata(AVCodecContext *avctx,
 }
 layout = ff_vorbis_ch_layouts[channels - 1].u.mask;
 channel_reorder = channel_reorder_vorbis;
-} else
-layout = 0;
+} else if (map_type == 2) {
+int ambisonic_order = ff_sqrt(channels) - 1;
+int idx = (ambisonic_order + 1) * (ambisonic_order + 1);
+if (channels <= 227 && (channels == idx || channels == idx + 2)) {
+av_channel_layout_uninit(>ch_layout);
+avctx->ch_layout.order = AV_CHANNEL_ORDER_AMBISONIC;
+avctx->ch_layout.nb_channels = channels;
+
+/* ACN order, followed by two optional channels of 
non-diegetic stereo */
+if (idx != channels)
+avctx->ch_layout.u.mask = AV_CH_LAYOUT_STEREO;
+} else {
+av_log(avctx, AV_LOG_ERROR, "Channel map 2 is only valid for "
+   "channel counts equal to (n + 1)^2 + 2j for {n,j} >= 0 "
+   "(max 227 channels).\n");
+return AVERROR_INVALIDDATA;
+}
+}
 
 channel_map = extradata + 21;
 } else {
@@ -415,11 +432,14 @@ av_cold int ff_opus_parse_extradata(AVCodecContext *avctx,
 }
 }
 
-av_channel_layout_uninit(>ch_layout);
-if (layout)
-av_channel_layout_from_mask(>ch_layout, layout);
-else
-av_channel_layout_default(>ch_layout, channels);
+if (avctx->ch_layout.order == AV_CHANNEL_ORDER_NATIVE) {
+av_channel_layout_uninit(>ch_layout);
+if (layout)
+av_channel_layout_from_mask(>ch_layout, layout);
+else
+av_channel_layout_default(>ch_layout, channels);
+}
+
 s->nb_streams = streams;
 s->nb_stereo_streams  = stereo_streams;
 
-- 
2.13.1

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