[FFmpeg-devel] [PATCH] avcodec/libtwolame: fix mono default bitrate

[James Cowgill]

As of libtwolame 0.4.0, 384 kbps is not accepted as a valid bitrate
for encoding mono audio and the maximum bitrate is now halved to 192
kbps to comply with the MP2 standard. Example error:

    twolame_init_params(): 384kbps is an invalid bitrate for mono encoding.

Adjust the default bitrate calculation to take this into account.

Signed-off-by: James Cowgill <jcowgill at debian.org>
---
 libavcodec/libtwolame.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/libavcodec/libtwolame.c b/libavcodec/libtwolame.c
index 030f88868f..5ceb3d9f3f 100644
--- a/libavcodec/libtwolame.c
+++ b/libavcodec/libtwolame.c
@@ -78,8 +78,12 @@ static av_cold int twolame_encode_init(AVCodecContext *avctx)
     twolame_set_in_samplerate(s->glopts, avctx->sample_rate);
     twolame_set_out_samplerate(s->glopts, avctx->sample_rate);
 
-    if (!avctx->bit_rate)
-        avctx->bit_rate = avctx->sample_rate < 28000 ? 160000 : 384000;
+    if (!avctx->bit_rate) {
+        if ((s->mode == TWOLAME_AUTO_MODE && avctx->channels == 1) || s->mode == TWOLAME_MONO)
+            avctx->bit_rate = avctx->sample_rate < 28000 ? 80000 : 192000;
+        else
+            avctx->bit_rate = avctx->sample_rate < 28000 ? 160000 : 384000;
+    }
 
     if (avctx->flags & AV_CODEC_FLAG_QSCALE || !avctx->bit_rate) {
         twolame_set_VBR(s->glopts, TRUE);
-- 
2.24.0.rc1