So I've noticed how some video files are able to be played back in Firefox. Some are not able to what so ever, for example I've created a text video using this FFPMEG command: ffmpeg -f lavfi -i testsrc=duration=10:size=1280x720:rate=30 testsrc.mp4
which created the following file: Both the uploaded version and the local .mp4 are unable to be played back in Firefox. However opening them up in edge chromium both files play back perfectly. Besides Edge I've also confirmed it plays back nicely in MPV.
also tried ffmpeg -i input.mp4 -vcodec libx265 -crf 20 output.mp4Tried changing -crf between 18 to 24, used both libx264,265 but it all resulted in nearly same output size, sometimes it even got bigger instead of smaller.
The manual of a DVD player says it plays .mp4 file format on the USB, some users still failed to play MP4 on it. Why does it happen? This is probably because your MP4 is encoded with a codec that your DVD player doesn't support. As a container format, MP4 can hold multiple video and audio codecs in it. Due to codec incompatible issue, you may hear the audio but can't see video, or you may get neither audio nor video. An error massage may pop up saying unsupported file type.
And you need to know that when a DVD player says it can play mpeg4, it doesn't mean that it can play video file with .mp4 extension. And it usually means that it supports MPEG 4 part 2 encoded video in an AVI container, namely AVI with Xvid/DivX. For example, some DVD players can play MP4 with DivX or Xvid, but can't play MP4 with H.264 codec. Therefore, you need to check the manual of your DVD player model and see what codecs and formats it accept from the USB. After that, you can use the following transcoding process to fix the DVD player won't MP4 issue.
To copy the video from invideo0.mp4 and the audio from inaudio1.mp3 and mux together with the audio starting from 15.5 seconds and cutting after a duration of 30 seconds and the video keeping just the first 40 seconds (so the last 10 seconds of the output will be silent):
ffmpeg -i "input.mp4" -vf "scale=trunc(iw/4)*2:trunc(ih/4)*2" /output.mp4In this example, the size is divided by twice the value required and then multiplied by two to ensure the pixel size is a multiple of two, which is required for some codecs.
All mp4 files contain a moov atom (flvs do not). The moov atom contains information about the length of the video and the audio and video tracks available in the .mp4 container. It acts as an index of the video data and the information in it enables the video player to play and scrub the .mp4 file. 041b061a72