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

1 files changed, 16 insertions, 0 deletions

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.