Doom9's Forum - View Single Post - [x /H264]: moov atom at the front of the file (Fast Start)

LoRd_MuldeR · 5th July 2015, 15:10

You can think of the moov atom is something like the global "index table" of the MP4 file. It can be located at the beginning of the file (before mdat atom) or at the end of the file (after mdat atom).

For local file playback it doesn't matter much, but for streaming (progressive download) you want to have the moov atom at the beginning of the file - for obvious reasons.

However, x264 will append the frames to the MP4 file as they are encoded. And, since the exact size of each frame cannot be known before they have actually been encoded, the index (moov atom) will be written last, at the end of the file.

So you cannot make x264 output an MP4 file with moov atom at the beginning. At least not directly. But you can achieve this easily with a tool like MP4Box or AtomicParsley!

Code:

mp4box.exe -add c:\Temp\input.mp4 c:\Temp\output.mp4

5th July 2015, 15:10	#3 \| Link
LoRd_MuldeR Software Developer Join Date: Jun 2005 Location: Last House on Slunk Street Posts: 13,248	You can think of the moov atom is something like the global "index table" of the MP4 file. It can be located at the beginning of the file (before mdat atom) or at the end of the file (after mdat atom). For local file playback it doesn't matter much, but for streaming (progressive download) you want to have the moov atom at the beginning of the file - for obvious reasons. However, x264 will append the frames to the MP4 file as they are encoded. And, since the exact size of each frame cannot be known before they have actually been encoded, the index (moov atom) will be written last, at the end of the file. So you cannot make x264 output an MP4 file with moov atom at the beginning. At least not directly. But you can achieve this easily with a tool like MP4Box or AtomicParsley! Code: mp4box.exe -add c:\Temp\input.mp4 c:\Temp\output.mp4 __________________ Go to https://standforukraine.com/ to find legitimate Ukrainian Charities 🇺🇦✊ Last edited by LoRd_MuldeR; 5th July 2015 at 15:23.