When using h.264 I use preset=placebo option. It increases encoding efficiency, but I don’t know I feel like it is also increasing decoding time. Is it right or it doesn’t affect decoding time at all? Answer You can use null muxer to test it. As stated in Null – FFmpeg The null muxer does not … Read more
I have a collection of avi videos (say A). I first convert them into MPEG4 Part2 (say B) using ffmpeg -i ${inname} -vf scale=340:256,setsar=1:1 -q:v 1 -c:v mpeg4 -g 12 -f rawvideo ${outname}. The total file size is 3.5G. Then using B as input, I apply the same command to transcode B again into C, … Read more
I have an mp4 file encoded using mpeg4 with a size of 20MB When I checked the details of it, it said it has a 308k variable bitrate Then, when I encoded it into h264, ffmpeg converted it with a constant 800k bitrate As a result, the file size became 60MB How do I get … Read more
I am writting program for recording IP cameras videos. I use Aforge framework and can save video in avi format, but it’s size is too big. I need some command line program to convert videos from avi to mpeg4 format. Is there any free program and if yes where can I download them and how … Read more
I have a corrupted MP4 file whose length is 25 minutes, but fter the first 4 minutes it jumps ahead to 20 minutes and one cannot playback the middle portion. It appears as though the index is corrupted. I re-encoded it as AVI using AVIDemux, with MPEG4-ASP as the output profile, but the resulting video … Read more
I have an mpeg4 stream contained in a matroska container which appears to give: $ ffmpeg -y -hide_banner -i input.mkv -c copy output.mkv [mpeg4 @ 0x5623e5204900] Failed to parse extradata Input #0, matroska,webm, from ‘input.mkv’: Metadata: ENCODER : Lavf58.20.100 Duration: 01:07:47.92, start: 0.000000, bitrate: 1433 kb/s Stream #0:0: Video: mpeg4 (Advanced Simple Profile), yuv420p, 688×512 … Read more
I’m decrypting an audible audiobook using this command: ffmpeg -audible_key KEY -audible_iv IV -i book.aax -c copy out.m4b The output file seems fine on my Windows machine. Metadata and cover are are present. But when I copy the file to my android device, the cover art isn’t loaded (CX File Explorer and Smart Audiobook Player). … Read more
I have two H.264 encoded MPEG-4 files that I need to concatenate. I have been using MP4Box for this task by first ensuring the files are encoded identically (even went so far as to compare output from h264_parse on their video tracks) and then concatenating with this command: MP4Box -cat file1.mp4 -cat file2.mp4 output_file.mp4 This … Read more
I have a few digital camera movies recorded in MJPEG that are taking a few GB of storage space. I would like to better compress them, but losing as little detail as possible, or none. Since MJPEG doesn’t compress across frames, I think that any modern movie codec would do a better job, wouldn’t it? … Read more
I have downloaded some computer science lectures from YouTube recently. There is usually more than one choice of file size and file format to download. I noticed that for the same video, the downloadable one with FLV 240 extension is larger than another one with MPEG4 360 extension. What does the number (240 and 360) mean? … Read more
