Hi Marton, On Thu, Jan 16, 2025 at 8:52 PM Marton Balint <c...@passwd.hu> wrote: > On Tue, 7 Jan 2025, Marton Balint wrote: > > Fixes corruption with: > > > > ffmpeg -t 1 -filter_complex > > "sine=f=21,showwaves=scale=cbrt:mode=line:colors=white:draw=full" -c:v > > mpeg2video -non_linear_quant 1 -qmin 1 -qmax 1 -cpuflags 0 out.mpg > > > > or > > > > ffmpeg -t 1 -filter_complex > > "sine=f=21,showwaves=scale=cbrt:mode=line:colors=white:draw=full" -c:v > > mpeg2video -non_linear_quant 1 -qmin 1 -qmax 1 -trellis 1 out.mpg > > > > Ping for this.
I checked that your examples do indeed get fixed by this patch, and also without -cpuflags 0 on x86. It would be great if we could add more comments about the range for the coefficients after the fdct, to make it clearer why the overflow happened. I wanted to do a more thorough check on the x86 code, and started adding dct_quantize to checkasm. The idea was to also check for overflow in multiple cases (mpeg/jpeg input range, jpeg/mpeg2/mpeg4, mb_intra...) but I gave up after trying to split the minimum necessary code to test dct_quantize from ff_mpv_encode_init. I will probably look into this in the future again, unless someone else wants to do it. All that just to say that the patch looks good to me as-is, but more work could be done afterwards. Ramiro _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
