[vlc-devel] [PATCH 1/2] ts: fix demuxing of BluRay streams.

[Rafaël Carré]

Hello Petri,

Would you have a sample for these TS?

On 02/04/14 23:37, Petri Hintukainen wrote:
> BluRay streams have 4-byte header before TS sync byte. Current code handles 192-byte ts packets,
> but it assumes extra bytes are at the end of packet. This results in re-sync at stream start:
>   1) first packet is dropped
>      First packet is usually PAT, and losing it means losing the first GOP.
>      This is fatal with still-image based menus.
>   2) 4-byte header of the second packet is skipped
>      This results in read of the last packet returning only 188 bytes,
>      and it is also skipped.
> ---
>  modules/demux/ts.c | 27 ++++++++++++++++++++++-----
>  1 file changed, 22 insertions(+), 5 deletions(-)
> 
> diff --git a/modules/demux/ts.c b/modules/demux/ts.c
> index f6c6fef..1acb938 100644
> --- a/modules/demux/ts.c
> +++ b/modules/demux/ts.c
> @@ -285,6 +285,9 @@ struct demux_sys_t
>      /* TS packet size (188, 192, 204) */
>      int         i_packet_size;
>  
> +    /* Additional TS packet header size (BluRay TS packets have 4-byte header before sync byte) */
> +    int         i_packet_header_size;
> +
>      /* how many TS packet we read at once */
>      int         i_ts_read;
>  
> @@ -385,13 +388,15 @@ static void SetPrgFilter( demux_t *, int i_prg, bool b_selected );
>  #define TS_PACKET_SIZE_MAX 204
>  #define TS_TOPFIELD_HEADER 1320
>  
> -static int DetectPacketSize( demux_t *p_demux )
> +static int DetectPacketSize( demux_t *p_demux, int *pi_header_size )
>  {
>      const uint8_t *p_peek;
>      if( stream_Peek( p_demux->s,
>                       &p_peek, TS_PACKET_SIZE_MAX ) < TS_PACKET_SIZE_MAX )
>          return -1;
>  
> +    *pi_header_size = 0;
> +
>      if( memcmp( p_peek, "TFrc", 4 ) == 0 )
>      {
>  #if 0
> @@ -483,6 +488,10 @@ static int DetectPacketSize( demux_t *p_demux )
>                   p_peek[i_sync + 2 * TS_PACKET_SIZE_192] == 0x47 &&
>                   p_peek[i_sync + 3 * TS_PACKET_SIZE_192] == 0x47 )
>          {
> +            if( i_sync == 4 )
> +            {
> +                *pi_header_size = 4; /* BluRay TS packets have 4-byte header */
> +            }
>              return TS_PACKET_SIZE_192;
>          }
>          else if( p_peek[i_sync + 1 * TS_PACKET_SIZE_204] == 0x47 &&
> @@ -554,12 +563,12 @@ static int Open( vlc_object_t *p_this )
>      demux_t     *p_demux = (demux_t*)p_this;
>      demux_sys_t *p_sys;
>  
> -    int          i_packet_size;
> +    int          i_packet_size, i_packet_header_size = 0;
>  
>      ts_pid_t    *pat;
>  
>      /* Search first sync byte */
> -    i_packet_size = DetectPacketSize( p_demux );
> +    i_packet_size = DetectPacketSize( p_demux, &i_packet_header_size );
>      if( i_packet_size < 0 )
>          return VLC_EGENERIC;
>  
> @@ -596,6 +605,7 @@ static int Open( vlc_object_t *p_this )
>      /* PID 8191 is padding */
>      p_sys->pid[8191].b_seen = true;
>      p_sys->i_packet_size = i_packet_size;
> +    p_sys->i_packet_header_size = i_packet_header_size;
>      p_sys->b_udp_out = false;
>      p_sys->fd = -1;
>      p_sys->i_ts_read = 50;
> @@ -1875,6 +1885,13 @@ static block_t* ReadTSPacket( demux_t *p_demux )
>          return NULL;
>      }
>  
> +    /* Skip header (BluRay streams).
> +     * re-sync logic would do this (by adjusting packet start), but this would result in losing first and last ts packets.
> +     * First packet is usually PAT, and losing it means losing whole first GOP. This is fatal with still-image based menus.
> +     */
> +    p_pkt->p_buffer += p_sys->i_packet_header_size;
> +    p_pkt->i_buffer -= p_sys->i_packet_header_size;
> +
>      /* Check sync byte and re-sync if needed */
>      if( p_pkt->p_buffer[0] != 0x47 )
>      {
> @@ -1895,8 +1912,8 @@ static block_t* ReadTSPacket( demux_t *p_demux )
>  
>              while( i_skip < i_peek - p_sys->i_packet_size )
>              {
> -                if( p_peek[i_skip] == 0x47 &&
> -                        p_peek[i_skip + p_sys->i_packet_size] == 0x47 )
> +                if( p_peek[i_skip + p_sys->i_packet_header_size] == 0x47 &&
> +                        p_peek[i_skip + p_sys->i_packet_header_size + p_sys->i_packet_size] == 0x47 )
>                  {
>                      break;
>                  }
>