From be233a569165ad39a63ff2137763a123cd4f2562 Mon Sep 17 00:00:00 2001
From: Justin Ruggles <justin.ruggles@gmail.com>
Date: Sun, 19 Apr 2009 14:05:55 +0000
Subject: [PATCH] Check that channel layout is compatible with number of
 channels for output audio stream.

Originally committed as revision 18621 to svn://svn.ffmpeg.org/ffmpeg/trunk
---
 ffmpeg.c                  | 2 ++
 libavcodec/audioconvert.c | 9 +++++++++
 libavcodec/audioconvert.h | 4 ++++
 3 files changed, 15 insertions(+)

diff --git a/ffmpeg.c b/ffmpeg.c
index 200d57dfef..c050512ae2 100644
--- a/ffmpeg.c
+++ b/ffmpeg.c
@@ -3212,6 +3212,8 @@ static void new_audio_stream(AVFormatContext *oc)
         audio_enc->channels = audio_channels;
         audio_enc->sample_fmt = audio_sample_fmt;
         audio_enc->channel_layout = channel_layout;
+        if (avcodec_channel_layout_num_channels(channel_layout) != audio_channels)
+            audio_enc->channel_layout = 0;
 
         if(codec && codec->sample_fmts){
             const enum SampleFormat *p= codec->sample_fmts;
diff --git a/libavcodec/audioconvert.c b/libavcodec/audioconvert.c
index b0a8afacb4..5842801093 100644
--- a/libavcodec/audioconvert.c
+++ b/libavcodec/audioconvert.c
@@ -153,6 +153,15 @@ void avcodec_get_channel_layout_string(char *buf, int buf_size, int nb_channels,
     }
 }
 
+int avcodec_channel_layout_num_channels(int64_t channel_layout)
+{
+    int count;
+    uint64_t x = channel_layout;
+    for (count = 0; x; count++)
+        x &= x-1; // unset lowest set bit
+    return count;
+}
+
 struct AVAudioConvert {
     int in_channels, out_channels;
     int fmt_pair;
diff --git a/libavcodec/audioconvert.h b/libavcodec/audioconvert.h
index 157bd44e21..46ba3d3929 100644
--- a/libavcodec/audioconvert.h
+++ b/libavcodec/audioconvert.h
@@ -73,6 +73,10 @@ void avcodec_get_channel_layout_string(char *buf, int buf_size, int nb_channels,
  */
 int64_t avcodec_guess_channel_layout(int nb_channels, enum CodecID codec_id, const char *fmt_name);
 
+/**
+ * @return the number of channels in the channel layout.
+ */
+int avcodec_channel_layout_num_channels(int64_t channel_layout);
 
 struct AVAudioConvert;
 typedef struct AVAudioConvert AVAudioConvert;