----- Original Message ----- From: Andy Shaules To: This list is about using libavcodec, libavformat, libavutil,libavdevice and libavfilter. Sent: Saturday, November 23, 2013 4:07 AM Subject: Re: [Libav-user] packet flag AV_PKT_FLAG_KEY
On 11/23/2013 12:05 AM, Don Moir wrote: ----- Original Message ----- From: Andy Shaules To: This list is about using libavcodec, libavformat, libavutil,libavdevice and libavfilter. Sent: Saturday, November 23, 2013 12:55 AM Subject: Re: [Libav-user] packet flag AV_PKT_FLAG_KEY On 11/22/2013 7:47 PM, Don Moir wrote: >>>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. >>>Is it not a application flag ? >>>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 :) >>>What if there are no index_entries ? Whats a key packet then and how to >>>determine ? >>>Just trying to clear up my own confusion with this. >>For h264, the key frame network abstraction unit of the packet will be of >>type IDR, instant data refresh. >>I believe NAL type 5. >>Thanks Andy. >>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. >>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. >Imagine H264 at HD resolution with 5 or 6 horizontal slices where the key >frame only equals one horizontal strip 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 ?
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