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.
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Imagine H264 at HD resolution with 5 or 6 horizontal slices where the
key frame only equals one horizontal strip of macro blocks. So yes, it
may or may not be a full key frame, but it should be an IDR packet.
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