Hi All, Any comments on my below query?
Also, is there any other group specifically for nvidia codec for ffmpeg? thanks, Sreenath On 3/3/16, Sreenath BH <[email protected]> wrote: > Hi all, > > I am trying to use nvidia's nvenc codec to transcode video files. > ffmpeg has been built > with both libx264 and nvenc codecs enabled. > > ffmpeg when run using nvenc codec creates a file that is almost double > the size of input > mp4 file and bitrate almost double the size of input file. > > This is output of ffprobe on the input file: > > Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'large.mp4': > Metadata: > Duration: 01:49:12.30, start: 0.000000, bitrate: 391 kb/s > Stream #0:0(eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p, > 768x432 [SAR 1:1 DAR 16:9], 292 kb/s, 30 fps, 30 tbr, 30 tbn, 60 tbc > (default) > Metadata: > creation_time : 2013-11-15 18:04:27 > handler_name : Apple Video Media Handler > > ----- Command used with libx264: > ffmpeg -i large.mp4 -loglevel quiet -c:a aac -c:v libx264 -pix_fmt > yuv420p -movflags +faststart out.mp4 > > output file has size of : 313818971 bytes > ffprobe output on the output file: > > Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'out.mp4': > Metadata: > encoder : Lavf57.25.100 > Duration: 01:49:12.30, start: 0.023220, bitrate: 383 kb/s > Stream #0:0(eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p, > 768x432 [SAR 1:1 DAR 16:9], 245 kb/s, 30 fps, 30 tbr, 15360 tbn, 60 > tbc (default) > Metadata: > handler_name : VideoHandler > > -------- Command using nvenv codec: > ffmpeg -i large.mp4 -loglevel quiet -c:a aac -c:v nvenc -pix_fmt > yuv420p -movflags +faststart out.mp4 > > Size of output file: > 646598462 bytes (640 MB) > > ffprobe output on the output files are as follows: > > Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'out.mp4': > Metadata: > encoder : Lavf57.25.100 > Duration: 01:49:12.30, start: 0.023220, bitrate: 789 kb/s > Stream #0:0(eng): Video: h264 (Main) (avc1 / 0x31637661), > yuv420p(tv), 768x432 [SAR 1:1 DAR 16:9], 654 kb/s, 30 fps, 30 tbr, > 15360 tbn, 60 tbc (default) > Metadata: > handler_name : VideoHandler > > So the differences between the two appear to be: > > (1) pixel format : yuv420p(tv) with nvidia whereas it is yuv420p with > libx264 > (2) h264 (Main) with nvidia whereas it is Video: h264 (High) > (3) bitrate: 789 kb/s with nvidia whereas it is 383 kb/s with lib264. > > What is causing nvidia codec to double the bitrate? As can be seen, I > am not specifying any bitrate to use. So I expect ffmpeg to retain the > same bitrate. > > I would like to retain the same bitrate and it would be good is the > file size if not so large. > > Any help appreciated, > > thanks, > Sreenath > _______________________________________________ Libav-user mailing list [email protected] http://ffmpeg.org/mailman/listinfo/libav-user
