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• Transcode to ogg or webm, writing the file as it goes

  22 juillet 2020, par Mark Smith

  I need to transcode files (mp3, flac, m4a and others) to ogg or webm. (This is because I need them to play on Firefox 60.9 which does not support most of these, and flacs are too large. I cannot update the browser.)

  


  ffmpeg can do the transcoding, but when transcoding to ogg or webm, depending on the exact configuration, either 0 bytes or a few kB is written immediately, and then nothing more until the transcoding is complete (even using -flush_packets 1) — hence I cannot start playing the audio.

  


  By comparison, if I transcode to mp3, the file is written progressively and I can start playing immediately.

  


  Is it possible to transcode to ogg or webm in such a way that the file is written as the transcoding happens, and I can start playing it (almost) immediately ?

  


  Configurations I have tried :

  


  ffmpeg -i orig.m4a -c:a libvorbis -flush_packets 1 vorbis.ogg
ffmpeg -i orig.m4a -c:a libopus -flush_packets 1 opus.ogg
ffmpeg -i orig.m4a -c:a libvorbis -flush_packets 1 vorbis.webm
ffmpeg -i orig.m4a -c:a libopus -flush_packets 1 opus.webm


  


  This is running on Debian (Raspian stretch, specifically) and I would like to do it without adding dependencies from outside of the Debian/Raspian archives, if possible. Sticking with ffmpeg would be my ideal choice but will consider others.

  


• ffmpeg : a way to write to a temp file and rename when finished writing ?

  29 juin 2023, par desktop1234

  i am using ffmpeg to split a video into frames and wondering if there any flags i can set so that ffmpeg will start writing the frame to a file and only rename it when its finished writing to it.

  


  for context this is the current ffmpeg command im using :

  


  ffmpeg -loglevel 8 -ss -to -copyts -i -vf -vsync passthrough -compression_level 1 -frame_pts true -sws_flags lanczos

  


  for further context, i am asking since i have set up a watcher on the directory ffmpeg writes to but i dont want to do anything with the file until its been fully written to and closed.

  


  i also dont want to rename every file when the full ffmpeg operation has completed, since it would defeat the purpose of my watcher, but rather as soon as 1 file has been fully written to, rename it.

  


  any help would be greatly appreciated !

  


• Use FFMPEG to stream images from one client to another through IIS (or other) server

  20 avril 2012, par eselk

  I'm new to FFMPEG and maybe I should post this in their forums, but you guys here seem to know everything, so here goes. I have a client app that takes screen shots and saves them as images (256 color bitmaps currently, can change if needed), it does this at a rate of about 4 fps. I currently use my own socket code written in C# to push these to my socket server (also C#) running on a Windows 2008 server. That server then sends these images out to several clients that display them as they are received and also buffers them to allow for rewind, pause, etc, like a DVR. My current format requires approx 100KB per frame, and thus only works for a very small number of clients.

  I started looking at FFMPEG and the compression with MPEG1 and especially MPEG4 is amazing, and so is the quality. What I'm looking for is a basic guide, tutorial, or steps, to produce something similar to my current design, but using FFMPEG and actual video streaming. Ideally the player side could be something like Flash or anything that is easy to embed in a .NET WinForm (or a browser control I can host in the WinForm), and it would need to support buffering still so they can pause and rewind (about 5 or 10 mins, which seems like a lot, but remember this is only 4 fps and 256 color, about 1 or 2 MB per min in my testing).

  I see that FFMPEG, the command-line utility, and I assume the API, even has options for posting to a server via UDP or TCP, so maybe I'll use that instead of my own socket code. Ideally my app would feed images to FFMPEG library at a rate of 4fps as they come from the screen-shot unit, and it would send these up to my IIS server (or another server ?) which would then server them to client(s) that could use them similar to a YouTube video.