The metadata can be placed after media data. In such case a progressive or faststart playback is not feasible a player should download all media data and then getting metadata and then starting playback.
Fortunately, ffmpeg has an option '-movflags faststart' to re-arrange boxes in mp4-file such that metadata located prior to media data 'mdat'. To move the medata to the beginning use the flag '-movflags faststart':. Note on Bitrate Box 'btrt'. How to interpret the bitrate. There are many ways to compute the bitrate and each way might provide different result.
Two parameters specify the bitrate measurement: the window length in seconds or in frames , the step size in seconds or in frames , for example:. Note, if the frame rate is The ISO base media file format Part 12, edition specifies the parameter maxBitrate in btrt-box as follows:. So, one deduces from this statement that window-size is 1s. Practically it's uneasy to measure the bitrate with the step size below the frame duration.
There is the pdf-file with more detailed explanation of fragmented mp4 structure:. Fragmented mp4 file structure shortly can be described as. However, ffmpeg has a bug in encapsulation into fmp4 - no composition time offsets are signaled :. If B frames are used in the input stream then sample composition time offset should be signaled in trun-box of each segment moof.
For information, for every sample in the segment the trun-box specifies the following fields:. Sample size in bytes. Sample composition time offset, actually equal to pts-dts. Sample flags. Each field is signaled optionally, if the field is not present then default values specified in another atom — tfhd are taken.
QuickTime player. How to determine whether an input mp4-file is regular or fragmented? The easiest way is to look for moof-boxes which are mandatory and specific in the fragmented mp4-file structure. Fragments are always signaled in pairs — 'moof-mdat'. Usually each GOP is stored in a separate moof-mdat pair it's called fragmentation at key frames if each GOP starts from a key frame. In addition to 'moof' and 'mdat' boxes the fragmet contains also 'mfhd' and 'traf s ' boxes.
Fragments can be in two modes:. Single Track : moof-mdat atoms for each track, in such case one traf box is signaled. My suggestion to set to the start of each moof and update all offsets within the current moof beginning from the moof-start. If sample flags are signaled n the original we need update them and signal in the output file.
The demuxer is more flexible — it requires the same codecs, but different container formats can be used; and it can be used with any container formats, while the protocol only works with a select few containers. In order to run this script you will need a shell like bash or zsh. Unix systems will come with this built in In MacOS terminal is a bash shell. If you are on the latest version of Windows 10 you also have bash now! Next, you will need a program called curl. Curl is a HTTP client, which basically means it downloads and uploads web stuff.
Hello Simon, great tutorial, thank you. I used your skript and code example to encode one of my videos and it plays just fine in firefox. The problem seems to occur at into the video. Happens with Firefox and Chrome for me. I would suggest linking to the version of Video.
That may give you a better idea of what the problem is. Hi Simon, thank you for your quick response. I have an updated version with the NOT minified videojs and it works with no errors!
Now I have multiple. Is there a way to force the browser to load the enc. I did a quick test with VideoJS and it appears to ignore it. I also tried hls. It works fine using Video. So, my question is: Is it possible to run one single ffmpeg command, and generate al the files you mentioned in the post, plus the.
Take a look at the dash muxer.
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