improve lame audio quality by using ABR mode and disabling joint stereo mode

add mp3 muxing into mp4 container.  cli and gtk gui now support this.


git-svn-id: svn://svn.handbrake.fr/HandBrake/trunk@3167 b64f7644-9d1e-0410-96f1-a4d463321fa5

2 files changed, 38 insertions, 2 deletions

diff --git a/libhb/enclame.c b/libhb/enclame.c
index 027aa3add..a3f4a3882 100644
--- a/libhb/enclame.c
+++ b/libhb/enclame.c
@@ -48,10 +48,19 @@ int enclameInit( hb_work_object_t * w, hb_job_t * job )
     hb_log( "enclame: opening libmp3lame" );
 
     pv->lame = lame_init();
-    lame_set_brate( pv->lame, audio->config.out.bitrate );
+    // use ABR
+    lame_set_VBR( pv->lame, vbr_abr );
+    lame_set_VBR_mean_bitrate_kbps( pv->lame, audio->config.out.bitrate );
     lame_set_in_samplerate( pv->lame, audio->config.out.samplerate );
     lame_set_out_samplerate( pv->lame, audio->config.out.samplerate );
     lame_init_params( pv->lame );
+    // Lame's default encoding mode is JOINT_STEREO.  This subtracts signal
+    // that is "common" to left and right (within some threshold) and encodes
+    // it separately.  This improves quality at low bitrates, but hurts 
+    // imaging (channel separation) at higher bitrates.  So if the bitrate
+    // is suffeciently high, use regular STEREO mode.
+    if ( audio->config.out.bitrate >= 128 )
+        lame_set_mode( pv->lame, STEREO );
 
     pv->input_samples = 1152 * 2;
     pv->output_bytes = LAME_MAXMP3BUFFER;
diff --git a/libhb/muxmp4.c b/libhb/muxmp4.c
index dcab2e5a6..01ba94004 100644
--- a/libhb/muxmp4.c
+++ b/libhb/muxmp4.c
@@ -347,7 +347,8 @@ static int MP4Init( hb_mux_object_t * m )
                     (const uint8_t*)(audio->config.out.name),
                     strlen(audio->config.out.name));
             }
-        } else {
+        } else if( audio->config.out.codec == HB_ACODEC_FAAC ||
+                   audio->config.out.codec == HB_ACODEC_CA_AAC ) {
             mux_data->track = MP4AddAudioTrack(
                 m->file,
                 audio->config.out.samplerate, 1024, MP4_MPEG4_AUDIO_TYPE );
@@ -376,6 +377,32 @@ static int MP4Init( hb_mux_object_t * m )
 
             /* Set the correct number of channels for this track */
              MP4SetTrackIntegerProperty(m->file, mux_data->track, "mdia.minf.stbl.stsd.mp4a.channels", (uint16_t)HB_AMIXDOWN_GET_DISCRETE_CHANNEL_COUNT(audio->config.out.mixdown));
+        } else if( audio->config.out.codec == HB_ACODEC_LAME ) {
+            mux_data->track = MP4AddAudioTrack(
+                m->file,
+                audio->config.out.samplerate, 1152, MP4_MPEG2_AUDIO_TYPE );
+
+            /* Tune track chunk duration */
+            MP4TuneTrackDurationPerChunk( m, mux_data->track );
+
+            if (audio->config.out.name == NULL) {
+                MP4SetTrackBytesProperty(
+                    m->file, mux_data->track,
+                    "udta.name.value",
+                    (const uint8_t*)"Stereo", strlen("Stereo"));
+            }
+            else {
+                MP4SetTrackBytesProperty(
+                    m->file, mux_data->track,
+                    "udta.name.value",
+                    (const uint8_t*)(audio->config.out.name),
+                    strlen(audio->config.out.name));
+            }
+
+            MP4SetAudioProfileLevel( m->file, 0x0F );
+
+            /* Set the correct number of channels for this track */
+             MP4SetTrackIntegerProperty(m->file, mux_data->track, "mdia.minf.stbl.stsd.mp4a.channels", (uint16_t)HB_AMIXDOWN_GET_DISCRETE_CHANNEL_COUNT(audio->config.out.mixdown));
         }
 
         /* Set the language for this track */