> On 25 Jun 2021, at 21:51, Dave Stevens <[email protected]> wrote: > > > I see there's more discussion but apart from the specifics of this instance > it's a general rule that there will always be files that get larger for a > compression attempt. If this were not so one could repeatedly compress a file > to any arbitrary degree. > > Dave >
That holds for lossless compression, but is less applicable for the sort of schemes used in video compression where quality is often traded for size. https://youtu.be/icruGcSsPp0 > > > >> On Friday 25/06/2021 at 1:12 pm, [email protected] wrote: >> >>> >>> try a larger value for -crf >> >> OK. The initial value was crf 18 and I now used crf=27 with a better result. >> I also took my original video, uploaded and downloaded it to youtube to see >> what youtube accomplishes, and here are the results: >> >> Original file: 18MB >> CRF=18: 25 MB >> CRF=27: 11.5 MB >> Youtube: 8.6MB >> >> I extracted stream info with ffprobe and here are some values. I'm not sure >> if these ones are the relevant ones; if more are required please let me >> know: >> >> ORIGINAL: >> r_frame_rate=60/1 >> avg_frame_rate=56724480/945439 ~ 60/1 >> bit_rate=2376739 >> nb_frames=3693 >> ------------------ >> COMPRESSED CRF 18 >> r_frame_rate=60/1 >> avg_frame_rate=60/1 >> bit_rate=3233826 >> nb_frames=3694 >> ------------------ >> COMPRESSED CRF 27 >> r_frame_rate=60/1 >> avg_frame_rate=60/1 >> bit_rate=1408499 >> nb_frames=3694 >> ------------------- >> Youtube: >> r_frame_rate=30/1 >> avg_frame_rate=30/1 >> bit_rate=1011745 >> nb_frames=1847 >> ------------------------------ >> >> What seems significant to me here is that YouTube reduced the frame rate and >> consequently the number of frames to half. The quality of the video still >> seems reasonably to what I need it for, so is there a command in ffmpeg >> where I can reduce the frame rate and accomplish the same as YouTube? >> >> Thanks >> >> >> -----Original Message----- >> From: ffmpeg-user <[email protected]> On Behalf Of Michael Koch >> Sent: Friday, June 25, 2021 10:07 PM >> To: [email protected] >> Subject: Re: [FFmpeg-user] Compressed file is larger than original... >> >>> Am 25.06.2021 um 20:40 schrieb [email protected]: >>> >>> I'm trying to reduce the size of an mp4 file to adjust it for >>> streaming. The video is about one minute long and I used the sample >>> command shown in https://trac.ffmpeg.org/wiki/Encode/YouTube. >>> >>> >>> >>> The original file size is ~18MB while the compressed file ended up at >> 25MB. >>> >>> While would the compressed file be larger? >>> >>> >>> >>> Below is the ffmpeg output: >>> >>> >>> >>> ffmpeg -i HBR_TT747.mp4 -c:v libx264 -preset slow -crf 18 -c:a copy >>> -pix_fmt yuv420p HBR_TT747_Compressed.mp4 >> >> try a larger value for -crf >> >> Michael >> >> _______________________________________________ >> ffmpeg-user mailing list >> [email protected] >> https://ffmpeg.org/mailman/listinfo/ffmpeg-user >> >> To unsubscribe, visit link above, or email [email protected] >> with subject "unsubscribe". >> >> >> _______________________________________________ >> ffmpeg-user mailing list >> [email protected] >> https://ffmpeg.org/mailman/listinfo/ffmpeg-user >> >> To unsubscribe, visit link above, or email >> [email protected] with subject "unsubscribe". > > _______________________________________________ > ffmpeg-user mailing list > [email protected] > https://ffmpeg.org/mailman/listinfo/ffmpeg-user > > To unsubscribe, visit link above, or email > [email protected] with subject "unsubscribe". _______________________________________________ ffmpeg-user mailing list [email protected] https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email [email protected] with subject "unsubscribe".
