[FFmpeg-devel] [PATCH 1/3] mp3enc: fix Xing sample rate selection.

[Clément Bœsch]

From: Clément Bœsch <clement.boesch at smartjog.com>

This at least avoid raising an unsupported sample rate warning when
sample rate is different than the sampling rate allowed in MPEG-1.

ex: ffmpeg -f lavfi -i aevalsrc=0 -ar 22050 -y /tmp/out.mp3
---
 libavformat/mp3enc.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/libavformat/mp3enc.c b/libavformat/mp3enc.c
index b2c1b42..d28e95c 100644
--- a/libavformat/mp3enc.c
+++ b/libavformat/mp3enc.c
@@ -126,7 +126,9 @@ static int mp3_write_xing(AVFormatContext *s)
         return 0;
 
     for (i = 0; i < FF_ARRAY_ELEMS(avpriv_mpa_freq_tab); i++)
-        if (avpriv_mpa_freq_tab[i] == codec->sample_rate) {
+        if (codec->sample_rate == avpriv_mpa_freq_tab[i]      ||    // MPEG 1
+            codec->sample_rate == avpriv_mpa_freq_tab[i] >> 1 ||    // MPEG 2 (LSF)
+            codec->sample_rate == avpriv_mpa_freq_tab[i] >> 2) {    // MPEG 2.5 (LSF)
             srate_idx = i;
             break;
         }
-- 
1.7.9.1