[FFmpeg-devel] [PATCH]Support *law in alsa

Carl Eugen Hoyos cehoyos at ag.or.at
Wed Apr 13 13:47:09 CEST 2011


Surprisingly, attached patch works with -f alsa plughw - audio encoded in 
mulaw or alaw is played fine (SND_PCM_FORMAT_IMA_ADPCM leads to division by 
zero, and with a work-around, I can only hear - recognisable - noise, somebody 
else will have to fix/explain).

If nobody objects (I did not check if there is a supported Alsa version that 
does not define the formats), I will apply together with the unsigned versions 
of the already supported formats.

Carl Eugen
-------------- next part --------------
diff --git a/libavdevice/alsa-audio-common.c b/libavdevice/alsa-audio-common.c
index 8ebe389..b4fb158 100644
--- a/libavdevice/alsa-audio-common.c
+++ b/libavdevice/alsa-audio-common.c
@@ -47,6 +47,8 @@ static av_cold snd_pcm_format_t codec_id_to_pcm_format(int codec_id)
         case CODEC_ID_PCM_S16LE: return SND_PCM_FORMAT_S16_LE;
         case CODEC_ID_PCM_S16BE: return SND_PCM_FORMAT_S16_BE;
         case CODEC_ID_PCM_S8:    return SND_PCM_FORMAT_S8;
+        case CODEC_ID_PCM_ALAW:  return SND_PCM_FORMAT_A_LAW;
         default:                 return SND_PCM_FORMAT_UNKNOWN;

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