[FFmpeg-devel] [PATCH 14/17] avcodec/mlpenc: Simplify channel layout comparisons

[Andreas Rheinhardt <andreas.rheinhardt@outlook.com>]

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).

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
---
 libavcodec/mlpenc.c | 30 ++++++++++++++----------------
 1 file changed, 14 insertions(+), 16 deletions(-)

diff --git a/libavcodec/mlpenc.c b/libavcodec/mlpenc.c
index 463332593f..d2e28888f7 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;
-- 
2.34.1

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