[Libav-user] JPEG decoder

[cyril apan]

>Hi All
>

>When using the JPEG decoder (CODEC_ID_MJPEG) sometimes I find that decoded frames are inverted/upside down/back to front. Having read into the problem I believe the issue is to do with the fact that bitmap is sometimes stored bottom-up in JPEG files.
>

>Does the decoder not realign the frame correctly or is this something that I would have to take care of after the decoding? If anyone can suggest the best way to deal with this I would appreciate it.
>

>Thanks,
>Mark.
You'll have to read metadata (Exif most of the time) to know what is the orientation of the stored bitmap and then process it to get the right rendering.
I don't think ffmpeg has any facility to read Exif metadata but you can use filters to do the rotation/flipping job.

Regards,

Cyril APAN.
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