libhb: Use h.264 recovery points as key frames when decoding

Many transport streams have few or zero IDR frames.  So scanning them 
takes a long time, generates a lot of log spam, and results in poor 
preview quality.  Often there will be several identical preview frames 
because it will find the same IDR for several of the previews.  Using 
recovery points helps all these problems.


git-svn-id: svn://svn.handbrake.fr/HandBrake/trunk@4180 b64f7644-9d1e-0410-96f1-a4d463321fa5

3 files changed, 164 insertions, 27 deletions

diff --git a/libhb/internal.h b/libhb/internal.h
index c4b30ee4a..c93a01af2 100644
--- a/libhb/internal.h
+++ b/libhb/internal.h
@@ -264,6 +264,7 @@ int          hb_stream_seek( hb_stream_t *, float );
 int          hb_stream_seek_ts( hb_stream_t * stream, int64_t ts );
 int          hb_stream_seek_chapter( hb_stream_t *, int );
 int          hb_stream_chapter( hb_stream_t * );
+int          hb_stream_recovery_count( hb_stream_t * );
 
 hb_buffer_t * hb_ts_decode_pkt( hb_stream_t *stream, const uint8_t * pkt );
 
diff --git a/libhb/scan.c b/libhb/scan.c
index 43b4825bc..764fd001b 100644
--- a/libhb/scan.c
+++ b/libhb/scan.c
@@ -614,6 +614,9 @@ static int DecodePreviews( hb_scan_t * data, hb_title_t * title )
                   hb_log( "Warning: Could not read data for preview %d, skipped", i + 1 );
                   goto skip_preview;
               }
+              int count = hb_stream_recovery_count( data->stream );
+              if ( count )
+                vidskip = count - 1;
             }
             else
             {
diff --git a/libhb/stream.c b/libhb/stream.c
index 30736cdad..adc42b622 100644
--- a/libhb/stream.c
+++ b/libhb/stream.c
@@ -48,7 +48,7 @@ static const stream2codec_t st2codec[256] = {
     st(0x03, A, HB_ACODEC_FFMPEG,  CODEC_ID_MP2,   "MPEG1"),
     st(0x04, A, HB_ACODEC_FFMPEG,  CODEC_ID_MP2,   "MPEG2"),
     st(0x05, N, 0,                 0,              "ISO 13818-1 private section"),
-    st(0x06, U, 0,                 0,              "ISO 13818-1 PES private data"),
+    st(0x06, N, 0,                 0,              "ISO 13818-1 PES private data"),
     st(0x07, N, 0,                 0,              "ISO 13522 MHEG"),
     st(0x08, N, 0,                 0,              "ISO 13818-1 DSM-CC"),
     st(0x09, N, 0,                 0,              "ISO 13818-1 auxiliary"),
@@ -158,6 +158,7 @@ struct hb_stream_s
 #define         TS_HAS_RAP  (1 << 1)    // Random Access Point bit seen
 #define         TS_HAS_RSEI (1 << 2)    // "Restart point" SEI seen
     uint8_t ts_IDRs;            // # IDRs found during duration scan
+    int     recovery_frames;
 
 
     char    *path;
@@ -199,6 +200,13 @@ struct hb_stream_s
     } pmt_info;
 };
 
+typedef struct {
+    uint8_t *buf;
+    uint32_t val;
+    int pos;
+    int size;
+} bitbuf_t;
+
 /***********************************************************************
  * Local prototypes
  **********************************************************************/
@@ -216,6 +224,10 @@ static hb_title_t *ffmpeg_title_scan( hb_stream_t *stream, hb_title_t *title );
 hb_buffer_t *hb_ffmpeg_read( hb_stream_t *stream );
 static int ffmpeg_seek( hb_stream_t *stream, float frac );
 static int ffmpeg_seek_ts( hb_stream_t *stream, int64_t ts );
+static inline unsigned int get_bits(bitbuf_t *bb, int bits);
+static inline void set_buf(bitbuf_t *bb, uint8_t* buf, int bufsize, int clear);
+static inline int buf_eob(bitbuf_t *bb);
+static inline int read_ue(bitbuf_t *bb );
 
 /*
  * streams have a bunch of state that's learned during the scan. We don't
@@ -1033,6 +1045,95 @@ static void skip_to_next_pack( hb_stream_t *src_stream )
     }
 }
 
+static void CreateDecodedNAL( uint8_t **dst, int *dst_len,
+                              const uint8_t *src, int src_len )
+{
+    const uint8_t *end = &src[src_len];
+    uint8_t *d = malloc( src_len );
+
+    *dst = d;
+
+    if( d )
+    {
+        while( src < end )
+        {
+            if( src < end - 3 && src[0] == 0x00 && src[1] == 0x00 &&
+                src[2] == 0x01 )
+            {
+                // Next start code found
+                break;
+            }
+            if( src < end - 3 && src[0] == 0x00 && src[1] == 0x00 &&
+                src[2] == 0x03 )
+            {
+                *d++ = 0x00;
+                *d++ = 0x00;
+
+                src += 3;
+                continue;
+            }
+            *d++ = *src++;
+        }
+    }
+    *dst_len = d - *dst;
+}
+
+static int isRecoveryPoint( const uint8_t *buf, int len )
+{
+    uint8_t *nal;
+    int nal_len;
+    int ii, type, size, start;
+    int recovery_frames = 0;
+
+    CreateDecodedNAL( &nal, &nal_len, buf, len );
+
+    for ( ii = 0; ii+1 < nal_len; )
+    {
+        start = ii;
+        type = 0;
+        while ( ii+1 < nal_len )
+        {
+            type += nal[ii++];
+            if ( nal[ii-1] != 0xff )
+                break;
+        }
+        size = 0;
+        while ( ii+1 < nal_len )
+        {
+            size += nal[ii++];
+            if ( nal[ii-1] != 0xff )
+                break;
+        }
+
+        if ( ii + size + 1 > nal_len )
+        {
+            // Is it an SEI recovery point?
+            if ( type == 6 )
+            {
+                // Recovery point found, but can't parse the entire NAL.
+                // So return an arbitrary recovery_frames count.
+                recovery_frames = 3;
+            }
+            break;
+        }
+
+        // Is it an SEI recovery point?
+        if ( type == 6 )
+        {
+            bitbuf_t bb;
+            set_buf(&bb, nal+ii, size, 0);
+            int count = read_ue( &bb );
+            recovery_frames = count + 3;
+            break;
+        }
+
+        ii += size;
+    }
+
+    free( nal );
+    return recovery_frames;
+}
+
 static int isIframe( hb_stream_t *stream, const uint8_t *buf, int adapt_len )
 {
     // For mpeg2: look for a gop start or i-frame picture start
@@ -1042,7 +1143,8 @@ static int isIframe( hb_stream_t *stream, const uint8_t *buf, int adapt_len )
     uint32_t strid = 0;
 
 
-    if ( stream->ts[0].stream_type <= 2 )
+    int vid = index_of_video(stream);
+    if ( stream->ts[vid].stream_type <= 2 )
     {
         // This section of the code handles MPEG-1 and MPEG-2 video streams
         for (i = 13 + adapt_len; i < 188; i++)
@@ -1076,7 +1178,7 @@ static int isIframe( hb_stream_t *stream, const uint8_t *buf, int adapt_len )
         // didn't find an I-frame
         return 0;
     }
-    if ( stream->ts[0].stream_type == 0x1b )
+    if ( stream->ts[vid].stream_type == 0x1b )
     {
         // we have an h.264 stream 
         for (i = 13 + adapt_len; i < 188; i++)
@@ -1087,14 +1189,23 @@ static int isIframe( hb_stream_t *stream, const uint8_t *buf, int adapt_len )
                 // we found a start code - remove the ref_idc from the nal type
                 uint8_t nal_type = strid & 0x1f;
                 if ( nal_type == 0x05 )
+                {
                     // h.264 IDR picture start
                     return 1;
+                }
+                else if ( nal_type == 0x06 )
+                {
+                    int off = i + 1;
+                    int recovery_frames = isRecoveryPoint( buf+off, 188-off );
+                    if ( recovery_frames )
+                        return recovery_frames;
+                }
             }
         }
         // didn't find an I-frame
         return 0;
     }
-    if ( stream->ts[0].stream_type == 0xea )
+    if ( stream->ts[vid].stream_type == 0xea )
     {
         // we have an vc1 stream 
         for (i = 13 + adapt_len; i < 188; i++)
@@ -1297,6 +1408,23 @@ static struct pts_pos hb_sample_pts(hb_stream_t *stream, uint64_t fpos)
                 ++stream->ts_IDRs;
             }
         }
+        pp.pos = ftello(stream->file_handle);
+        if ( !stream->ts_IDRs )
+        {
+            // Scan a little more to see if we will stumble upon one
+            int ii;
+            for ( ii = 0; ii < 10; ii++ )
+            {
+                buf = hb_ts_stream_getPEStype( stream, pid, &adapt_len );
+                if ( buf == NULL )
+                    break;
+                if ( isIframe( stream, buf, adapt_len ) )
+                {
+                    ++stream->ts_IDRs;
+                    break;
+                }
+            }
+        }
     }
     else
     {
@@ -1308,8 +1436,8 @@ static struct pts_pos hb_sample_pts(hb_stream_t *stream, uint64_t fpos)
             skip_to_next_pack( stream );
         }
         pp.pts = hb_ps_stream_getVideoPTS( stream );
+        pp.pos = ftello(stream->file_handle);
     }
-    pp.pos = ftello(stream->file_handle);
     return pp;
 }
 
@@ -1583,19 +1711,10 @@ int hb_stream_seek( hb_stream_t * stream, float f )
         // forwards to the next transport stream packet.
         hb_ts_stream_reset(stream);
         align_to_next_packet(stream);
-        if ( f > 0 )
-        {
-            if ( stream->ts_IDRs )
-            {
-                // the stream has IDRs so look for one.
-                stream->need_keyframe = 1;
-            }
-        }
-        else
+        if ( stream->ts_IDRs )
         {
-            // we're at the beginning - say we have video sync so that we
-            // won't drop initial SPS & PPS data on an AVC stream.
-            stream->need_keyframe = 0;
+            // the stream has IDRs so look for one.
+            stream->need_keyframe = 1;
         }
     }
     else if ( stream->hb_stream_type == program )
@@ -2148,13 +2267,6 @@ static off_t align_to_next_packet(hb_stream_t *stream)
     return start - orig + pos;
 }
 
-
-typedef struct {
-    uint8_t *buf;
-    uint32_t val;
-    int pos;
-} bitbuf_t;
-
 static const unsigned int bitmask[] = {
     0x0,0x1,0x3,0x7,0xf,0x1f,0x3f,0x7f,0xff,
     0x1ff,0x3ff,0x7ff,0xfff,0x1fff,0x3fff,0x7fff,0xffff,
@@ -2165,15 +2277,16 @@ static inline void set_buf(bitbuf_t *bb, uint8_t* buf, int bufsize, int clear)
 {
     bb->pos = 0;
     bb->buf = buf;
+    bb->size = bufsize;
     bb->val = (bb->buf[0] << 24) | (bb->buf[1] << 16) |
               (bb->buf[2] << 8) | bb->buf[3];
     if (clear)
         memset(bb->buf, 0, bufsize);
 }
 
-static inline int buf_size(bitbuf_t *bb)
+static inline int buf_eob(bitbuf_t *bb)
 {
-    return bb->pos >> 3;
+    return bb->pos >> 3 == bb->size;
 }
 
 static inline unsigned int get_bits(bitbuf_t *bb, int bits)
@@ -2205,6 +2318,17 @@ static inline unsigned int get_bits(bitbuf_t *bb, int bits)
     return val;
 }
 
+static inline int read_ue(bitbuf_t *bb )
+{
+    int ii = 0;
+
+    while( get_bits( bb, 1 ) == 0 && !buf_eob( bb ) && ii < 32 )
+    {
+        ii++;
+    }
+    return( ( 1 << ii) - 1 + get_bits( bb, ii ) );
+}
+
 // extract what useful information we can from the elementary stream
 // descriptor list at 'dp' and add it to the stream at 'esindx'.
 // Descriptors with info we don't currently use are ignored.
@@ -2757,6 +2881,13 @@ static void hb_ts_stream_append_pkt(hb_stream_t *stream, int idx, const uint8_t
     stream->ts[idx].buf->size += len;
 }
 
+int hb_stream_recovery_count( hb_stream_t *stream )
+{
+    int count = stream->recovery_frames;
+    stream->recovery_frames = 0;
+    return count;
+}
+
 /***********************************************************************
  * hb_ts_stream_decode
  ***********************************************************************
@@ -2926,7 +3057,9 @@ hb_buffer_t * hb_ts_decode_pkt( hb_stream_t *stream, const uint8_t * pkt )
         {
             // we're looking for the first video frame because we're
             // doing random access during 'scan'
-            if ( curstream != video_index || !isIframe( stream, pkt, adapt_len ) )
+            if ( curstream == video_index )
+                stream->recovery_frames = isIframe( stream, pkt, adapt_len );
+            if ( curstream != video_index || !stream->recovery_frames )
             {
                 // not the video stream or didn't find an I frame
                 // but we'll only wait 255 video frames for an I frame.