[FFmpeg-devel] meaning of AV_PKT_FLAG_KEY

Don Moir donmoir at comcast.net
Wed Dec 4 13:18:21 CET 2013

>----- Original Message ----- 
>From: "Michael Niedermayer" <michaelni at gmx.at>
>To: "FFmpeg development discussions and patches" <ffmpeg-devel at ffmpeg.org>
>Sent: Tuesday, December 10, 2013 7:49 PM
>Subject: Re: [FFmpeg-devel] meaning of AV_PKT_FLAG_KEY

>On Wed, Dec 04, 2013 at 07:44:53AM -0500, Don Moir wrote:
>> I asked about this 2 years ago in ticket and no answer there.
>> I asked in user and no answer there.
>> So asking here what is the meaning of AV_PKT_FLAG_KEY and does it have any meaining to an application ?
>> The comment for AV_PKT_FLAG_KEY says it represents a key packet. If you decode this packet, the frame indicates it's a key frame.
>> If packet contains AV_PKT_FLAG_KEY it does not necessarily reflect a timestamp in index_entries which are known to be keyframes 
>> if marked as such.
>> Would be damn useful is this flag was dependable as a keyframe or start of keyframe. Right now I don't know if its a bug or what 
>> it is supposed to mean.

>it means its a keyframe in the sense of a frame from which you can
>start decoding

Thats what I have been assuming it means more or less but wasn't quite sure. This was brought on by AVDISCARD_NONKEY not working 
across the board. AVDISCARD_NONKEY works much better now for h264 and the like, but still not reliable for others, so not a good 
general solution.

At least now I will know if  AV_PKT_FLAG_KEY is not working as expected, it's a bug :)


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