[FFmpeg-devel] current way to tell if image is bottom up-possible bug

Don Moir donmoir at comcast.net
Thu Aug 23 22:14:24 CEST 2012

----- Original Message ----- 
From: "Don Moir" <donmoir at comcast.net>
To: "FFmpeg development discussions and patches" <ffmpeg-devel at ffmpeg.org>
Sent: Thursday, August 23, 2012 2:51 PM
Subject: Re: [FFmpeg-devel] current way to tell if image is bottom 
up-possible bug

>> On 23/08/2012 2:26 PM, Don Moir wrote:
>>> So your saying extradata should contain "BottomUp" in this case? I 
>>> always
>>> thought this was a bit strange and thinking a flag should be used 
>>> instead.
>>> I don't know for sure if it ever worked in ffplay because I don't think
>>> ffplay ever checked for "BottomUp". Just saying its upside down in 
>>> ffplay.
>>> For me, I check for "BottomUp" and invert if necessary and no longer can 
>>> do.
>>> Just reply and I will report it as a bug.
>>i am not saying anything about extradata or BottomUp, just that if
>>it worked with ffplay in the past and no longer works then its likely
>>a bug, also if it works with some other player and doesnt work with
>>ffplay its likely a bug
>>To be able to say more i need a reproduceable testcase and sample
> I don't think it ever worked in ffplay but it worked in my app. Now it 
> appears you cannot tell if a video is bottom up or at least in the 
> following case.
> The method I use is to check extradata for "BottomUp" but no longer works. 
> If there was a better way, I would use it.
> http://sms.pangolin.com/temp/upside-down.avi

It appears CODEC_FLAG_EMU_EDGE prevents flipping of the image. Apparently 
something has changed where extradata "BottomUp" is not used anymore (or in 
this case) and the flip is done iternally if CODEC_FLAG_EMU_EDGE is not set. 

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