ffmpeg

问题 I am new to video encoding so bear with me. I am using FFMPEG. I have an mp4 file which is 640 x 350 with an average bitrate of around 2000kb (I think) and a filesize of 80Mb. I want to convert this to an ogv file with a much lower bit rate (128kb) but the same width and height. I am using the following command... ffmpeg -i input.mp4 -b:v 128k output.ogv ... but FFMPEG seems to ignore my bitrate option and outputs a file with a bitrate of around 600kb and a filesize of around 3Mb. I can do

问题 I am new to video encoding so bear with me. I am using FFMPEG. I have an mp4 file which is 640 x 350 with an average bitrate of around 2000kb (I think) and a filesize of 80Mb. I want to convert this to an ogv file with a much lower bit rate (128kb) but the same width and height. I am using the following command... ffmpeg -i input.mp4 -b:v 128k output.ogv ... but FFMPEG seems to ignore my bitrate option and outputs a file with a bitrate of around 600kb and a filesize of around 3Mb. I can do

问题 I have created a HLS stream from a FLAC file with an output of FLAC using the following command: ffmpeg -i 10-brass-in-pocket.flac -map 0:a -c:a:0 flac -f hls -hls_playlist_type vod -master_pl_name master.m3u8 -hls_time 30 -hls_segment_type fmp4 -strict -2 -hls_segment_filename music.m4s -hls_flags single_file -var_stream_map "a:0" stream_%v.m3u8` I have published it here: https://di5wym8npn4cm.cloudfront.net/stackoverflow_fmp4_singlefile/master.m3u8. (this works in VLC) Page with audio

问题 I have created a HLS stream from a FLAC file with an output of FLAC using the following command: ffmpeg -i 10-brass-in-pocket.flac -map 0:a -c:a:0 flac -f hls -hls_playlist_type vod -master_pl_name master.m3u8 -hls_time 30 -hls_segment_type fmp4 -strict -2 -hls_segment_filename music.m4s -hls_flags single_file -var_stream_map "a:0" stream_%v.m3u8` I have published it here: https://di5wym8npn4cm.cloudfront.net/stackoverflow_fmp4_singlefile/master.m3u8. (this works in VLC) Page with audio

问题 TL;DR I'm trying to programmatically download a part of a YouTube video. The widely known procedure doesn't work for some videos and I'd like to overcome this situation. Context I'm trying to programmatically download a part of a YouTube video. As described in How to download portion of video with youtube-dl command?, you can achieve this by the following commands. #Converts a human-readable URL to longer URLs for internal use. ~ $ youtube-dl --get-url 'https://www.youtube.com/watch?v

问题 The line ffmpeg -f h264 -i pipe111.fifo -c:v copy -f mp4 - gives the error: Input #0, h264, from 'pipe111.fifo': Duration: N/A, bitrate: N/A Stream #0:0: Video: h264 (Constrained Baseline), yuv420p, 480x270, 6 fps, 6 tbr, 1200k tbn, 12 tbc [mp4 @ 0x1562130] muxer does not support non seekable output Output #0, mp4, to 'pipe:': Metadata: encoder : Lavf56.9.100 Stream #0:0: Video: h264 ([33][0][0][0] / 0x0021), yuv420p, 480x270, q=2-31, 6 fps, 1200k tbn, 1200k tbc Stream #0:0 -> #0:0 (copy)

问题 The line ffmpeg -f h264 -i pipe111.fifo -c:v copy -f mp4 - gives the error: Input #0, h264, from 'pipe111.fifo': Duration: N/A, bitrate: N/A Stream #0:0: Video: h264 (Constrained Baseline), yuv420p, 480x270, 6 fps, 6 tbr, 1200k tbn, 12 tbc [mp4 @ 0x1562130] muxer does not support non seekable output Output #0, mp4, to 'pipe:': Metadata: encoder : Lavf56.9.100 Stream #0:0: Video: h264 ([33][0][0][0] / 0x0021), yuv420p, 480x270, q=2-31, 6 fps, 1200k tbn, 1200k tbc Stream #0:0 -> #0:0 (copy)

问题 I'm trying to achieve the Datamosh effect on video. (source: ilovenewwork.com) I know that in general what I need to the video is to delete all i-Frames but I have no idea how to achieve that using ffmpeg. 回答1: if you are just looking for an easy command line solution! install the following ruby script https://github.com/ucnv/aviglitch [nodejs version https://github.com/fand/node-aviglitch] convert your video to AVI ffmpeg -i input.mp4 output1.avi datamosh it with the ruby script "aviglitch"

问题 I'm trying to achieve the Datamosh effect on video. (source: ilovenewwork.com) I know that in general what I need to the video is to delete all i-Frames but I have no idea how to achieve that using ffmpeg. 回答1: if you are just looking for an easy command line solution! install the following ruby script https://github.com/ucnv/aviglitch [nodejs version https://github.com/fand/node-aviglitch] convert your video to AVI ffmpeg -i input.mp4 output1.avi datamosh it with the ruby script "aviglitch"

问题 I tried 3 methods to call ffmpeg from python, but it always blocks and doesn't return any result. However, if I execute it from shell, it works. For eg: /usr/bin/ffmpeg -y -i /tmp/uploadedfiles/movie8_15_10s.mpg -ar 1600 -ac 1 /tmp/uploadedfiles/movie8_15_10s.mpg.wav this works. However, ffmpeg_command = "/usr/bin/ffmpeg -y -i test.wav testout.wav" f_ffmpeg=os.popen(ffmpeg_command); This makes the python hang. 回答1: You should use subprocess.Popen instead of os.popen . In particular, to get