| .TH "MP4" "3" "Version 0.9" "Cisco Systems Inc." "MP4 File Format Library" |
| .SH "NAME" |
| .LP |
| \fBMP4AddRtpVideoHint\fR \- Add an RTP video specific hint |
| .SH "SYNTAX" |
| .LP |
| #include <mp4.h> |
| .LP |
| bool \fBMP4AddRtpVideoHint\fR( |
| .br |
| MP4FileHandle \fIhFile\fP, |
| .br |
| MP4TrackId \fItrackId\fP, |
| .br |
| bool \fIisBFrame\fP = false, |
| .br |
| u_int32_t \fItimestampOffset\fP = 0 |
| .br |
| ); |
| .SH "ARGUMENTS" |
| .LP |
| .TP |
| \fIhFile\fP |
| Specifies the mp4 file to which the operation applies. |
| .TP |
| \fItrackId\fP |
| Specifies the hint track to which the operation applies. |
| .TP |
| \fIisBFrame\fP |
| Specifies if this hint will contain packets for a video B frame |
| .TP |
| \fItimestampOffset\fP |
| Specifies a positive offset to add to the RTP timestamp for this hint. Caveat: the value is in the hint track timescale. |
| .SH "RETURN VALUES" |
| .LP |
| Upon success, true (1). Upon an error, false (0). |
| .SH "DESCRIPTION" |
| .LP |
| \fBMP4AddRtpVideoHint\fR is an extended version of MP4AddRtpHint specifically to handle MPEG video frames. |
| .LP |
| The isBFrame parameter allows the packets in the RTP hint to be marked as belonging to a video B frame. This can be useful to a streaming server if packets must be dropped due to system load or network congestion. No other video frames are dependent on the contents of B frames, so they are least damaging type of frames to drop. |
| .LP |
| The timestampOffset parameter allows an offset to be added to the RTP timestamp of the packets in the RTP hint. This is necessary for MPEG video that contains B frames since the video frames are transmitted out of order with respect to when they should be rendered. I.e I and P frames are transmitted before any B frames that depend on them. The RTP timestamp must represent the rendering time of the data in the packets hence an offset must be added. |
| .LP |
| Note: The timestampOffset is equivalent to the sample rendering offset of a video media track. See MP4GetSampleRenderingOffset(). |
| |
| .SH "SEE ALSO" |
| .LP |
| MP4(3) MP4AddRtpHint(3) MP4AddRtpPacket(3) MP4WriteRtpHint (3) |
