[FFmpeg-cvslog] avcodec/mlpenc: Simplify channel layout comparisons

[Andreas Rheinhardt]

ffmpeg | branch: master | Andreas Rheinhardt <andreas.rheinhardt at outlook.com> | Sat Sep 17 23:13:05 2022 +0200| [a12338afe5192f23349c0fde8592891be230bfc3] | committer: Andreas Rheinhardt

avcodec/mlpenc: Simplify channel layout comparisons

These encoders have AVCodec.ch_layouts set, so ff_encode_preinit()
has already checked that the used channel layout is equivalent
to one of these native layouts. Therefore one can simply
compare the channel masks (with the added complication
that one has to use av_channel_layout_subset() to get it,
because the channel layout is not guaranteed to have
AV_CHANNEL_ORDER_NATIVE).

Reviewed-by: Paul B Mahol <onemda at gmail.com>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at outlook.com>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=a12338afe5192f23349c0fde8592891be230bfc3
---

 libavcodec/mlpenc.c | 30 ++++++++++++++----------------
 1 file changed, 14 insertions(+), 16 deletions(-)

diff --git a/libavcodec/mlpenc.c b/libavcodec/mlpenc.c
index ac1f446313..18e8ce4579 100644
--- a/libavcodec/mlpenc.c
+++ b/libavcodec/mlpenc.c
@@ -480,6 +480,7 @@ static av_cold int mlp_encode_init(AVCodecContext *avctx)
     static AVOnce init_static_once = AV_ONCE_INIT;
     MLPEncodeContext *ctx = avctx->priv_data;
     RestartHeader *const rh = &ctx->restart_header;
+    uint64_t channels_present;
     unsigned int sum = 0;
     size_t size;
     int ret;
@@ -589,19 +590,20 @@ static av_cold int mlp_encode_init(AVCodecContext *avctx)
 
     ctx->num_substreams = 1; // TODO: change this after adding multi-channel support for TrueHD
 
+    channels_present = av_channel_layout_subset(&avctx->ch_layout, ~(uint64_t)0);
     if (ctx->avctx->codec_id == AV_CODEC_ID_MLP) {
-        static const AVChannelLayout layout_arrangement[] = {
-            AV_CHANNEL_LAYOUT_MONO,         AV_CHANNEL_LAYOUT_STEREO,
-            AV_CHANNEL_LAYOUT_2_1,          AV_CHANNEL_LAYOUT_QUAD,
-            AV_CHANNEL_LAYOUT_2POINT1,      { 0 }, { 0 },
-            AV_CHANNEL_LAYOUT_SURROUND,     AV_CHANNEL_LAYOUT_4POINT0,
-            AV_CHANNEL_LAYOUT_5POINT0_BACK, AV_CHANNEL_LAYOUT_3POINT1,
-            AV_CHANNEL_LAYOUT_4POINT1,      AV_CHANNEL_LAYOUT_5POINT1_BACK,
+        static const uint64_t layout_arrangement[] = {
+            AV_CH_LAYOUT_MONO,         AV_CH_LAYOUT_STEREO,
+            AV_CH_LAYOUT_2_1,          AV_CH_LAYOUT_QUAD,
+            AV_CH_LAYOUT_2POINT1,      0, 0,
+            AV_CH_LAYOUT_SURROUND,     AV_CH_LAYOUT_4POINT0,
+            AV_CH_LAYOUT_5POINT0_BACK, AV_CH_LAYOUT_3POINT1,
+            AV_CH_LAYOUT_4POINT1,      AV_CH_LAYOUT_5POINT1_BACK,
         };
         int i;
 
         for (i = 0; i < FF_ARRAY_ELEMS(layout_arrangement); i++)
-            if (!av_channel_layout_compare(&avctx->ch_layout, &layout_arrangement[i]))
+            if (channels_present == layout_arrangement[i])
                 break;
         if (i == FF_ARRAY_ELEMS(layout_arrangement)) {
             av_log(avctx, AV_LOG_ERROR, "Unsupported channel arrangement\n");
@@ -613,29 +615,25 @@ static av_cold int mlp_encode_init(AVCodecContext *avctx)
         ctx->summary_info      = ff_mlp_ch_info[ctx->channel_arrangement].summary_info     ;
     } else {
         /* TrueHD */
-        if (!av_channel_layout_compare(&avctx->ch_layout,
-                                       &(AVChannelLayout)AV_CHANNEL_LAYOUT_MONO)) {
+        if (channels_present == AV_CH_LAYOUT_MONO) {
             ctx->ch_modifier_thd0    = 3;
             ctx->ch_modifier_thd1    = 3;
             ctx->ch_modifier_thd2    = 3;
             ctx->channel_arrangement = 2;
             ctx->thd_substream_info  = 0x14;
-        } else if (!av_channel_layout_compare(&avctx->ch_layout,
-                                       &(AVChannelLayout)AV_CHANNEL_LAYOUT_STEREO)) {
+        } else if (channels_present == AV_CH_LAYOUT_STEREO) {
             ctx->ch_modifier_thd0    = 1;
             ctx->ch_modifier_thd1    = 1;
             ctx->ch_modifier_thd2    = 1;
             ctx->channel_arrangement = 1;
             ctx->thd_substream_info  = 0x14;
-        } else if (!av_channel_layout_compare(&avctx->ch_layout,
-                                              &(AVChannelLayout)AV_CHANNEL_LAYOUT_5POINT0)) {
+        } else if (channels_present == AV_CH_LAYOUT_5POINT0) {
             ctx->ch_modifier_thd0    = 1;
             ctx->ch_modifier_thd1    = 1;
             ctx->ch_modifier_thd2    = 1;
             ctx->channel_arrangement = 11;
             ctx->thd_substream_info  = 0x104;
-        } else if (!av_channel_layout_compare(&avctx->ch_layout,
-                                              &(AVChannelLayout)AV_CHANNEL_LAYOUT_5POINT1)) {
+        } else if (channels_present == AV_CH_LAYOUT_5POINT1) {
             ctx->ch_modifier_thd0    = 2;
             ctx->ch_modifier_thd1    = 1;
             ctx->ch_modifier_thd2    = 2;