libhb: work around the lack of 6.1 support for DTS sources

libhb doesn't support 6.1 sources and assumes they're 7.0 instead. This breaks downmixing.

Libav can decode the DTS-ES 6.1 core of DTS-HD 6.1 audio tracks; tell it to not process the additional channel so that such tracks can be re-encoded correctly.

See https://reviews.handbrake.fr/r/200/ for more information.



git-svn-id: svn://svn.handbrake.fr/HandBrake/trunk@4209 b64f7644-9d1e-0410-96f1-a4d463321fa5

4 files changed, 46 insertions, 0 deletions

diff --git a/libhb/decavcodec.c b/libhb/decavcodec.c
index f67850d86..4d62c0274 100644
--- a/libhb/decavcodec.c
+++ b/libhb/decavcodec.c
@@ -203,6 +203,24 @@ static int decavcodecaInit( hb_work_object_t * w, hb_job_t * job )
         return 1;
     }
 
+    // DTS: work around lack of 6.1 support in libhb
+    if( hb_ff_dts_request_5point1( pv->context ) )
+    {
+        hb_deep_log( 2, "decavcodecaInit: found DTS-ES 6.1, requesting 5.1 core" );
+    }
+    else if( ( !pv->context->channels || !pv->context->channel_layout ) &&
+             ( w->audio->config.in.codec == HB_ACODEC_DCA_HD ) &&
+             ( w->audio->config.in.channel_layout == ( HB_INPUT_CH_LAYOUT_3F2R|HB_INPUT_CH_LAYOUT_HAS_LFE ) ) )
+    {
+        /* XXX: when we are demuxing the stream ourselves, it seems we have no
+         * channel count/layout info in the context until we decode audio for
+         * the first time. If the scan info says the source is DTS-HD 5.1,
+         * make sure XCh processing is disabled in Libav before decoding. */
+        pv->context->request_channels = pv->context->channels = 6;
+        pv->context->channel_layout = AV_CH_LAYOUT_5POINT1;
+        hb_deep_log( 2, "decavcodecaInit: scan detected DTS 5.1, disabling XCh processing" );
+    }
+
     if ( w->audio != NULL )
     {
         if ( hb_need_downmix( w->audio->config.in.channel_layout, 
@@ -439,6 +457,11 @@ static int decavcodecaBSInfo( hb_work_object_t *w, const hb_buffer_t *buf,
                                              &out_size, &avp );
                 if ( len > 0 && context->sample_rate > 0 )
                 {
+                    // DTS: work around lack of 6.1 support in libhb
+                    if( hb_ff_dts_request_5point1( context ) )
+                    {
+                        hb_deep_log( 2, "decavcodecaBSInfo: found DTS-ES 6.1, requesting 5.1 core" );
+                    }
                     int isamp = av_get_bytes_per_sample( context->sample_fmt );
                     info->bitrate = context->bit_rate;
                     info->rate = context->sample_rate;
diff --git a/libhb/hb.c b/libhb/hb.c
index f9bbcdc83..8ca3918ad 100644
--- a/libhb/hb.c
+++ b/libhb/hb.c
@@ -316,6 +316,22 @@ void hb_ff_set_sample_fmt(AVCodecContext *context, AVCodec *codec)
     }
 }
 
+// Libav can decode DTS-ES 6.1 (5.1 core + XCh extension)
+// but we don't support 6.1 (and incorrectly assume 7.0)
+// request 6 channels to disable XCh processing in Libav
+int hb_ff_dts_request_5point1( AVCodecContext *c )
+{
+    if( ( c->codec_id == CODEC_ID_DTS ) &&
+        ( c->channels == 7 ) &&
+        ( c->channel_layout & ( AV_CH_BACK_CENTER|AV_CH_LOW_FREQUENCY ) ) )
+    {
+        c->request_channels = c->channels = 6;
+        c->channel_layout &= ~AV_CH_BACK_CENTER;
+        return 1;
+    }
+    return 0;
+}
+
 /**
  * Registers work objects, by adding the work object to a liked list.
  * @param w Handle to hb_work_object_t to register.
diff --git a/libhb/hbffmpeg.h b/libhb/hbffmpeg.h
index 495e90e67..f1ea4a704 100644
--- a/libhb/hbffmpeg.h
+++ b/libhb/hbffmpeg.h
@@ -18,4 +18,5 @@ hb_sws_get_context(int srcW, int srcH, enum PixelFormat srcFormat,
                    int dstW, int dstH, enum PixelFormat dstFormat,
                    int flags);
 void hb_ff_set_sample_fmt(AVCodecContext *context, AVCodec *codec);
+int hb_ff_dts_request_5point1( AVCodecContext *c );
 int hb_av_set_string( AVCodecContext *c, AVCodec *codec, const char *name, const char *val );
diff --git a/libhb/stream.c b/libhb/stream.c
index adc42b622..517e29ee4 100644
--- a/libhb/stream.c
+++ b/libhb/stream.c
@@ -3308,6 +3308,12 @@ static void add_ffmpeg_audio( hb_title_t *title, hb_stream_t *stream, int id )
     AVDictionaryEntry *tag;
     int layout;
 
+    // DTS: work around lack of 6.1 support in libhb
+    if( hb_ff_dts_request_5point1( codec ) )
+    {
+        hb_deep_log( 2, "add_ffmpeg_audio: found DTS-ES 6.1, requesting 5.1 core" );
+    }
+
     // scan will ignore any audio without a bitrate. Since we've already
     // typed the audio in order to determine its codec we set up the audio
     // paramters here.