[vdr] How does VDR handle AFD?
rnissl at gmx.de
Wed Sep 14 23:16:33 CEST 2005
Christian Gmeiner wrote:
> i am currently interested in this topic and wanted to know how VDR does
> handle this. If you dont know what AFD is:
> I think that VDR needs a menuentry where the user must specify what kind
> of tv-set he owns (4:3 or 16:9).
> If we add this we could make use of the AFD header in VDR. Maybe i am
> wrong and AFD is allready supported by VDR.
Well, I've added extracting AFD information in xine. But so far, I do
nothing more than storing this information as stream info.
As far as I can tell, VDR doesn't extract any AFD information from video
streams. But it should not be too complicated to add this to
cRemux::ScanVideoPacket(), due to the repacking of cVideoRepacker.
AFD information appears in the video stream after user data startcodes
(0x000001B2) and these appear before picture start codes (0x00000100).
Typically, there are only a few bytes between those startcodes. And as
cVideoRepacker ensures a new PES packet for each picture, AFD
information should be in the same 2048 byte block where
ScanVideoPacket() finds the picture start code.
The next few lines are from xine-lib/src/libmpeg2/decode.c:
/* check Active Format Description ETSI TS 101 154 V1.5.1 */
else if (buffer == 0x44 && buffer == 0x54 && buffer == 0x47 &&
buffer == 0x31)
int afd = (buffer & 0x40) ? (buffer & 0x0f) : -1;
_x_stream_info_set(mpeg2dec->stream, XINE_STREAM_INFO_VIDEO_AFD, afd);
And these are from xine-lib/include/xine.h:
/* possible values for XINE_STREAM_INFO_VIDEO_AFD */
#define XINE_VIDEO_AFD_NOT_PRESENT -1
#define XINE_VIDEO_AFD_RESERVED_0 0
#define XINE_VIDEO_AFD_RESERVED_1 1
#define XINE_VIDEO_AFD_BOX_16_9_TOP 2
#define XINE_VIDEO_AFD_BOX_14_9_TOP 3
#define XINE_VIDEO_AFD_BOX_GT_16_9_CENTRE 4
#define XINE_VIDEO_AFD_RESERVED_5 5
#define XINE_VIDEO_AFD_RESERVED_6 6
#define XINE_VIDEO_AFD_RESERVED_7 7
#define XINE_VIDEO_AFD_SAME_AS_FRAME 8
#define XINE_VIDEO_AFD_4_3_CENTRE 9
#define XINE_VIDEO_AFD_16_9_CENTRE 10
#define XINE_VIDEO_AFD_14_9_CENTRE 11
#define XINE_VIDEO_AFD_RESERVED_12 12
#define XINE_VIDEO_AFD_4_3_PROTECT_14_9 13
#define XINE_VIDEO_AFD_16_9_PROTECT_14_9 14
#define XINE_VIDEO_AFD_16_9_PROTECT_4_3 15
But don't expect this feature to be part of VDR-1.4.
Dipl.-Inform. (FH) Reinhard Nissl
mailto:rnissl at gmx.de
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