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<DIV><FONT face=Arial size=2>----- Original Message ----- <BR>From: Andy Shaules
<BR>To: This list is about using libavcodec, libavformat, libavutil,libavdevice
and libavfilter. <BR>Sent: Saturday, November 23, 2013 4:07 AM<BR>Subject: Re:
[Libav-user] packet flag AV_PKT_FLAG_KEY</FONT></DIV>
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<DIV><BR>On 11/23/2013 12:05 AM, Don Moir wrote:</DIV>
<DIV> </DIV>
<DIV><BR>----- Original Message ----- <BR>From: Andy Shaules <BR>To: This list
is about using libavcodec, libavformat, libavutil,libavdevice and libavfilter.
<BR>Sent: Saturday, November 23, 2013 12:55 AM<BR>Subject: Re: [Libav-user]
packet flag AV_PKT_FLAG_KEY</DIV>
<DIV> </DIV>
<DIV><BR>On 11/22/2013 7:47 PM, Don Moir wrote:</DIV>
<DIV> </DIV>
<DIV>>>>Not sure what AV_PKT_FLAG_KEY is supposed to mean. The
assumption to me early on is it represented a key frame but not
necessarily.</DIV>
<DIV> </DIV>
<DIV>>>>Is it not a application flag ?</DIV>
<DIV> </DIV>
<DIV>>>>Seems for at least H264 it doesnt have much meaning to
application. If the packet dts value is in the stream index_entires then that
represents a key frame for sure ( hopefully :)</DIV>
<DIV> </DIV>
<DIV>>>>What if there are no index_entries ? Whats a key packet then
and how to determine ?</DIV>
<DIV> </DIV>
<DIV>>>>Just trying to clear up my own confusion with this.</DIV>
<DIV> </DIV>
<DIV><BR>>>For h264, the key frame network abstraction unit of the packet
will be of type IDR, instant data refresh. <BR>>>I believe NAL type 5.
</DIV>
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<DIV>>>Thanks Andy. </DIV>
<DIV> </DIV>
<DIV>>>Dont see that info in a packet. Only thing relevant that changes is
the flags member (0 or 1). Now frame may contain additional info after decoding
but it's documented that >>AV_PKT_FLAG_KEY represents a keyframe.</DIV>
<DIV> </DIV>
<DIV>>>If it is for internal use, a different flag should have been used
the way I see it. So trying to understand what the real intended use of
AV_PKT_FLAG_KEY is.</DIV>
<DIV> </DIV>
<DIV><BR>>Imagine H264 at HD resolution with 5 or 6 horizontal slices where
the key frame only equals one horizontal strip</DIV>
<DIV> </DIV>
<DIV>Yeah I get that. It sure knows that a packet is a key packet when it adds
it to the index_entries but packet flag does not correspond. Seems like the
packet flag should correspond to the index_entries. Yes or No ?</DIV>
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