#Ffmpeg scale mp4#
#Ffmpeg scale software#

All the most common media codecs support it. In order to achieve the maximum efficiency (as in maximum quality for the given average bitrate), we want a higher bitrate for the most complex segments, and a lower bitrate for the simpler ones. When it comes to encoding a stream (either video or audio), we need to choose the strategy for allocating the amount of data. Result: the file won’t play! The player says that there is a limit in the frame size of 800圆00 since the input is 1280x720, we’ll need to resize.

this yields in general, a rough bitrate of 130 kbps, at whom the vast majority of people can’t distinguish an encoded file from the source on a blind test, with a good encoderĪlthough this is not a “tiny” amount of parameters, they’re all very explicit and logical.

like the video encoding, we use variable bitrate, with a quality factor of 5.

LAME is the reference (open source) MP3 encoder.

’ -c:a libmp3lame’: odec for the udio stream.

this yielded an 1.6 GiB video stream, which is overkill for a 1280x720 source.

we use variable bitrate, with a quality factor of 4.

we need to explicitly set this for maximum compatibility.

the default for mpeg is Xvid, which in essence, is the open source DivX competitor.

’ -c:v mpeg4’: odec for the ideo stream.

FFmpeg will choose the container automatically based on the extension, which in this case will be AVI.

This is the command:įfmpeg -i input.mp4 -c:v mpeg4 -vtag xvid -qscale:v 4 -c:a libmp3lame -qscale:a 5 output.avi As efficiency nerd, I’ll use variable bitrate encoding for both audio and video. First attempt: a basic audio/video conversion mkv), support subtitles and chapter markers (among other functionalities).ĪVI limitations will cause me a problem, as seen in the last section, but for this player, it’s the only choice.

#Ffmpeg scale mp4#

This must be kept in mind for example, “MP4 audio files” are a common source of confusion: technically, to be exact, MP4 is the container, while the audio stream encoding format is AAC.Ĭontainers have other characteristics. Note how I’ve separated the concept of “container” (AVI) and “streams” (video and audio). It has been for a long time used for distributions of movies whose video was encoded in the famous DivX format, which marked the beginning of the online movies piracy.Īs a matter of fact, to be specific, the player supports DivX video and MP3 audio streams stored in an AVI container. A brief introduction to video file related concepts and formatsĪfter reading the related section of the player manual, I gathered that the supported video format is AVI.ĪVI is a very old container format, and limited, by today’s standards. Modern Ubuntu versions ship with FFmpeg, although in the past, they shipped for a while with Libav.Ī good starting point for understanding the fork history is an LWN article, which strives to stay neutral.

#Ffmpeg scale software#

First attempt: a basic audio/video conversionįFmpeg is a “free and open-source project consisting of a vast software suite of libraries and programs for handling video, audio, and other media files and streams”.įrom a practical perspective, the user uses a single executable, ffmpeg, which, through a huge (but logical and consistent) amount of switches, can perform operations on media files.įFmpeg is (or better, has been) associated with Libav, a fork that has seen some success in the past, but it seems dead(-ish) in the present.įor the sake of this article, both are equivalent (except that the Libav binary is named avconv).A brief introduction to video file related concepts and formats.I will also explain general concepts of media handling, like containers and encoding formats. This post will give a glimpse of the tools that FFmpeg provides, showing how easy it is to perform the video/audio conversion, with extra processing.

Therefore, this was a good occasion to exercise the FFmpeg conversion and processing capabilities. The player was very old, and couldn’t handle the video file (a modern MP4). During my last vacation, I wanted to watch some very old cartoons, during the daily break, on the digital media player that the apartment provided.