[FFmpeg-cvslog] avcodec/ac3enc: Use bit-operations for bit-mask

[Andreas Rheinhardt]

ffmpeg | branch: master | Andreas Rheinhardt <andreas.rheinhardt at outlook.com> | Sun Apr  7 13:21:46 2024 +0200| [8261d5d38c93419535dbd81116fc1d065716e039] | committer: Andreas Rheinhardt

avcodec/ac3enc: Use bit-operations for bit-mask

Simply masking the LFE bit is more natural than subtracting
if set.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at outlook.com>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=8261d5d38c93419535dbd81116fc1d065716e039
---

 libavcodec/ac3enc.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/libavcodec/ac3enc.c b/libavcodec/ac3enc.c
index 1a65e35161..31b9474822 100644
--- a/libavcodec/ac3enc.c
+++ b/libavcodec/ac3enc.c
@@ -2199,10 +2199,8 @@ static av_cold void set_channel_info(AVCodecContext *avctx)
     s->channels     = channels;
     s->fbw_channels = channels - s->lfe_on;
     s->lfe_channel  = s->lfe_on ? s->fbw_channels + 1 : -1;
-    if (s->lfe_on)
-        mask -= AV_CH_LOW_FREQUENCY;
 
-    switch (mask) {
+    switch (mask & ~AV_CH_LOW_FREQUENCY) {
     case AV_CH_LAYOUT_MONO:           s->channel_mode = AC3_CHMODE_MONO;   break;
     case AV_CH_LAYOUT_STEREO:         s->channel_mode = AC3_CHMODE_STEREO; break;
     case AV_CH_LAYOUT_SURROUND:       s->channel_mode = AC3_CHMODE_3F;     break;