On Tue, Dec 23, 2014 at 08:12:50AM +0100, Stefano Sabatini wrote: > On date Monday 2014-12-22 17:57:34 +0100, Reimar Döffinger encoded: > > On 22.12.2014, at 17:23, Stefano Sabatini <stefa...@gmail.com> wrote: > [...] > > > I'm testing with: > > > ffmpeg -i matrixbench_mpeg2.mpg -b:v 200k matrixbench_mpeg2-lq.mpg > > > > > > ffplay -f lavfi -i "nullsrc=s=720x576 [bg]; > > > movie=matrixbench_mpeg2-lq.mpg:s=dv+da [v][out1]; [v]split[v1][v2]; > > > [v1]crop=in_w/2:in_h:0:0 [v1pp]; [v2]crop=in_w/2:in_h:in_w/2:0,fspp > > > [v2pp]; [bg][v1pp] overlay[bg+v1pp]; [bg+v1pp][v2pp] overlay=W/2 [out0]" > > > > > > I'm unable to see significant differences in terms of quality between > > > left and right part of the output (same with mp=fspp, so it doesn't > > > depend on the port). > > > > > > Is this expected? > > > > > > What's the use case of fspp? > > > > What codec did your lq version end up using? I suspect fspp is most > > tested and works best with MPEG-4 ASP. It should significantly > > reduce blocking - obviously only if your video has significant > > blocking. It used to work fairly well on early flv streaming > > videos. > > Output #0, mpeg, to 'matrixbench_mpeg2-lq.mpg': > Metadata: > encoder : Lavf56.16.101 > Stream #0:0: Video: mpeg1video, yuv420p, 720x576 [SAR 16:15 DAR 4:3], > q=2-31, 200 kb/s, 25 fps, 90k tbn, 25 tbc > Metadata: > encoder : Lavc56.16.100 mpeg1video > Stream #0:1: Audio: mp2, 48000 Hz, stereo, s16, 384 kb/s > Metadata: > encoder : Lavc56.16.100 mp2 > Stream mapping: > Stream #0:1 -> #0:0 (mpeg2video (native) -> mpeg1video (native)) > Stream #0:2 -> #0:1 (mp2 (native) -> mp2 (native))
It's possible fspp does not implement (correct) quantizer mapping for MPEG-1. Plus, MPEG-1 was pretty much irrelevant at the point it was implemented, so chance are it indeed never worked (at least not in a useful way) for MPEG-1. _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
