[FFmpeg-user] mp4 generate moov atom at beginning of recording

[simon mares]

On 08/19/2013 04:39 PM, Tom Evans wrote:
> On Sun, Aug 18, 2013 at 3:04 AM, simon mares <simon.mares at gmail.com> wrote:
>> Hello, is it possible to generate a pre-defined moov atom for fixed lenght
>> of fe. 8 hours with use of
>> http://ffmpeg.org/ffmpeg-all.html#MOV_002fMP4_002fISMV arguments? Video
>> would never be seeked beyond the real duration, as I would not allow.
>>
>> Reason for doing this is that I'm experimenting with something and I would
>> like to playback the file that I'm still recording, so it's kind of a
>> live-streaming, but it's only used locally. As I'm only transcoding from .ts
>> to .mp4 file no CPU is used, this is also my goal.
>>
>> Codec is h264, 720p, 25pfs. Video is generated with blackmagic pro-recorder.
>>
> Just use "-movflags faststart".
>
> Cheers
>
> Tom
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Hey
Thank you for answer.
I tried this, indeed ffmpeg did move moov atom in front of movie data 
(mdat) but when I open this video after 18 seconds of recoding and video 
*is still being recorded* then duration is 18 seconds in player, but 
video is still recording. What I would need that I would predefine this 
headers for some hours ahead.

Please note that I'm encoding from named pipe, so mp4 file is generated 
on-the-fly.

One more explanation

*Current state*:
1) Recording started (recording_01.mp4) from named pipe from video encoder
2) Video is being recorded for 18 seconds now and it continues to record
3) I open recording_01.mp4 in video player, duration is 18 seconds and 
I'm watching from start, 5 seconds
4) ffmpeg is still encoding to recording_01.mp4 ... duration 18, 19, 20, 
21 s, ...
5) when I come to 19 seconds video stops being played (point 3)

after 5 seconds of playing

0s   5s   10s   15s   20s
|-------------------------------| 23 sec rec_01.mp4
|----->----------------| 5 sec video player, duration 18 sec

*What I would like is following*:
1) Recording started (recording_01.mp4) from named pipe from video encoder
2) Video is being recorded for 18 seconds now and it continues to record
3) I open recording_01.mp4 in video player, duration is *3600* seconds 
and I'm watching from start
4) ffmpeg is still encoding to recording_01.mp4 ... duration 18, 19, 20, 
21 s, ...
5) when I come to 19 seconds video *doesnt stop* being played

0s   5s   10s   15s   20s
|-------------------------------| 23 sec rec_01.mp4
|----->---------------------------------- .... -----| 5 sec video 
player, duration 1 hour

Check points 3 and 5, where I put "*".

I hope it's more understandable now.

Cheers,

Simon