Get previews from H.264 content even if it's missing IDR frames (e.g., NZ TV & some blu-rays):

 - Grab stream characteristics (IDRs or not, PCRs or not, RAPs or not) while we're reading to compute the duration rather than trying to guess with no information later.
 - Only wait for an IDR after a seek if we know the stream has IDRs. Even then, wait for at most 255 frames.
 - If the stream doesn't have IDRs tell scan (via a new flag in the title struct) so that it can read but discard a second's worth of frames to get the decoder in sync withe stream.
 - While we're trying to sync the decoder, ffmpeg will spit out dozens of useless error messages so suppress them.


git-svn-id: svn://svn.handbrake.fr/HandBrake/trunk@2071 b64f7644-9d1e-0410-96f1-a4d463321fa5

1 files changed, 26 insertions, 0 deletions

diff --git a/libhb/scan.c b/libhb/scan.c
index 6459c1d50..6cdaceb62 100644
--- a/libhb/scan.c
+++ b/libhb/scan.c
@@ -439,6 +439,21 @@ static int DecodePreviews( hb_scan_t * data, hb_title_t * title )
         vid_decoder->codec_param = title->video_codec_param;
         vid_decoder->init( vid_decoder, NULL );
         hb_buffer_t * vid_buf = NULL;
+        int vidskip = 0;
+
+        if ( title->flags & HBTF_NO_IDR )
+        {
+            // title doesn't have IDR frames so we decode but drop one second's
+            // worth of frames to allow the decoder to converge.
+            if ( ! title->rate_base )
+            {
+                vidskip = 30;
+            }
+            else
+            {
+                vidskip = (double)title->rate / (double)title->rate_base + 0.5;
+            }
+        }
 
         for( j = 0; j < 10240 ; j++ )
         {
@@ -446,6 +461,10 @@ static int DecodePreviews( hb_scan_t * data, hb_title_t * title )
             {
               if( !hb_dvd_read( data->dvd, buf_ps ) )
               {
+                  if ( vid_buf )
+                  {
+                    break;
+                  }
                   hb_log( "Warning: Could not read data for preview %d, skipped", i + 1 );
                   goto skip_preview;
               }
@@ -470,6 +489,13 @@ static int DecodePreviews( hb_scan_t * data, hb_title_t * title )
                 if( buf_es->id == title->video_id && vid_buf == NULL )
                 {
                     vid_decoder->work( vid_decoder, &buf_es, &vid_buf );
+                    if ( vid_buf && vidskip && --vidskip > 0 )
+                    {
+                        // we're dropping frames to get the video decoder in sync
+                        // when the video stream doesn't contain IDR frames
+                        hb_buffer_close( &vid_buf );
+                        vid_buf = NULL;
+                    }
                 }
                 else if( ! AllAudioOK( title ) )
                 {