1MP4(3) MP4 File Format Library MP4(3)
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6 MP4AddRtpVideoHint - Add an RTP video specific hint
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9 #include <mp4.h>
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11 bool MP4AddRtpVideoHint(
12 MP4FileHandle hFile,
13 MP4TrackId trackId,
14 bool isBFrame = false,
15 u_int32_t timestampOffset = 0
16 );
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19 hFile Specifies the mp4 file to which the operation applies.
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21 trackId
22 Specifies the hint track to which the operation applies.
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24 isBFrame
25 Specifies if this hint will contain packets for a video B frame
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27 timestampOffset
28 Specifies a positive offset to add to the RTP timestamp for this
29 hint. Caveat: the value is in the hint track timescale.
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32 Upon success, true (1). Upon an error, false (0).
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35 MP4AddRtpVideoHint is an extended version of MP4AddRtpHint specifically
36 to handle MPEG video frames.
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38 The isBFrame parameter allows the packets in the RTP hint to be marked
39 as belonging to a video B frame. This can be useful to a streaming
40 server if packets must be dropped due to system load or network congesā
41 tion. No other video frames are dependent on the contents of B frames,
42 so they are least damaging type of frames to drop.
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44 The timestampOffset parameter allows an offset to be added to the RTP
45 timestamp of the packets in the RTP hint. This is necessary for MPEG
46 video that contains B frames since the video frames are transmitted out
47 of order with respect to when they should be rendered. I.e I and P
48 frames are transmitted before any B frames that depend on them. The RTP
49 timestamp must represent the rendering time of the data in the packets
50 hence an offset must be added.
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52 Note: The timestampOffset is equivalent to the sample rendering offset
53 of a video media track. See MP4GetSampleRenderingOffset().
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57 MP4(3) MP4AddRtpHint(3) MP4AddRtpPacket(3) MP4WriteRtpHint (3)
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61Cisco Systems Inc. Version 0.9 MP4(3)