On Sun, 3 Apr 2016 15:26:02 +0200 Michael Niedermayer <mich...@niedermayer.cc> wrote:
> On Sun, Apr 03, 2016 at 02:31:06PM +0200, Hendrik Leppkes wrote: > > On Sun, Apr 3, 2016 at 2:07 PM, Michael Niedermayer > > <mich...@niedermayer.cc> wrote: > > > Without this or some other change moving data back and forth corrupts it > > > as the cropped & possibly low res resolution modified w/h will be taken > > > a the pre lowres resolution > > > also without 2 sets theres no place to communicate the cropped dimensions > > > > > > can be reproduced with > > > ./ffplay_g -vlowres 2 tickets/162/avid.avi > > > > > > > lowres is supposed to be applied in the decoder, not the demuxer, so I > > don't see how this is required here. > > if iam not mistaken (please correct me if iam wrong) > > the demuxer runs a decoder, which initializes various AVCodecContext > fields these then get copied into AVCodecParameters and back into > the users AVCodecContext used for the user appliations decoder > > the first decoder will set width & height to the low resolution > with lowres, coded_width / height will represent the stored, true > width/height > the data copied into the AVCodecParameters will have lost the width > & height that is stored anywhere but rather contain the lowres > variant. > > the user app then will initialize its decoder based on coded_width > and coded_height which it will find set to 0 so it fallback to the > compatibility hack of using width & height which are the lowres > values and the decoder will apply the lowres stuff again > > above is based on some assumtations i have not verified very step with > a debugger > > > > AVCodecParameters is supposed to contain container information, not > > pre-interpreted info based on some decoding options. > This just shows how broken using decoders in libavformat is by design. The output parameters of a decoder have not necessarily anything to do with the input codec parameters. In any case, not sure why we'd care about an obscure semi-broken feature like lowres anyway. _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
