[Libav-user] Applied pad on the decoded frame

[Francesco Damato]

Hi Dolevo Jay,

i have a avi and mp4 file. The avcodec_encode_video2 function takes input
raw video data from frame, so i demux my file and i obtain a raw video
file; now i want encode it, so how i can open the raw file, read the raw
frames and encode them into h264??

Thanks for your help!!

Regards


2013/10/15 Dolevo Jay <cmst at live.com>

>
>
> > From: bruce at spearmorgan.com
> > Date: Mon, 14 Oct 2013 15:47:05 -0700
>
> > To: libav-user at ffmpeg.org
> > Subject: Re: [Libav-user] Applied pad on the decoded frame
> >
> > On Oct 14, 2013, at 4:46 AM, Dolevo Jay <cmst at live.com> wrote:
> >
> > > I have encoder and decoder application in separate projects. I use
> x264 to encode the incoming frames and use libav to decode them. If the
> frame has a specific resolution like 1366 x 768, the decode frame contains
> extra black border at the right side of the frame. I have debugged it and
> realized that the av_pic.linesize[0] is 50 more than the linesize during
> the encoding.
> > > Here is the code:
> > >
> > > lengthDec = avcodec_decode_video2(c1, av_pic, &pic, &pkt);
> > > if (pic)
> > > {
> > > avpicture_fill((AVPicture *)rgbFrame, RGBimg, PIX_FMT_RGB32, w, h);
> > > sws_scale(ctx, av_pic->data, av_pic->linesize, 0, h, rgbFrame->data,
> rgbFrame->linesize);
> > > }
> > >
> > > So, in this code, I decode the packet and convert the decoded data
> into the rgb.
> > > Why does the avcodec_decode_video2 returns a padded linesize?
> > > Could anyone tell me how I can eliminate the black border?
> >
> > The actual encoded data has padding, added to make encoding and decoding
> more efficient. The returned frame has the padding still, since it's more
> efficient again - just decoding into a buffer without having to copy all
> the lines.
> >
> > That's very standard. Expect to see that in almost all codecs and frame
> sizes.
> >
> > You need to use the viewable width, not the linesize when scaling.
> >
> > Bruce
> > _______________________________________________
> > Libav-user mailing list
> > Libav-user at ffmpeg.org
> > http://ffmpeg.org/mailman/listinfo/libav-user
>
>
> Thanks for your reply. I have described the problem in detail with some
> pictures here: http://forum.doom9.org/showthread.php?t=169036
> It is really strange that it produces no black part (bar) when I set the
> width = width+1 when calling sws_getContext. Could it be a bug in swscale
> since I do no scaling?
>
> Thanks a lot.
>
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>
>


-- 
Francesco Damato
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