How soon can an a video segment be ready for reading ?

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How soon can an a video segment be ready for reading ?

Subrata Goswami
Looks like when ffmpeg creates a video  segment, it is not possible to
start reading that  segment right away.  Throws  "moov atom not found"
 error .  So if I have a 30 sec  segment, I have to wait for at least 30
secs.    Tried the -movflags faststart option,   still throws the same
error.

Welcome any suggestion,
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Re: How soon can an a video segment be ready for reading ?

Carl Zwanzig
On 2/8/2019 4:33 PM, Subrata Goswami wrote:
> Welcome any suggestion,

...repost the question including the entire command line you've tried and
all of it's output. (Open-ended questions don't usually get a good response,
specific ones do- for instance, which codec/container are you using? that
matters, as does the version of ffmpeg.)

z!
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Re: How soon can an a video segment be ready for reading ?

Subrata Goswami
Sure , here is the command.

ffmpeg -y  -i <url> -map 0 -an -sn -dn -r 8/1 -movflags faststart -f
segment -segment_time 30 -segment_format mp4 -strftime 1 /tmp/%d_%s.mp4

Trying to read the file  as soon as it is written ( with a simple piece of
code) throws the following error.

[mov,mp4,m4a,3gp,3g2,mj2 @ 0x7f1a60002200] moov atom not found




On Fri, Feb 8, 2019 at 4:45 PM Carl Zwanzig <[hidden email]> wrote:

> On 2/8/2019 4:33 PM, Subrata Goswami wrote:
> > Welcome any suggestion,
>
> ...repost the question including the entire command line you've tried and
> all of it's output. (Open-ended questions don't usually get a good
> response,
> specific ones do- for instance, which codec/container are you using? that
> matters, as does the version of ffmpeg.)
>
> z!
> _______________________________________________
> ffmpeg-user mailing list
> [hidden email]
> http://ffmpeg.org/mailman/listinfo/ffmpeg-user
>
> To unsubscribe, visit link above, or email
> [hidden email] with subject "unsubscribe".
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Re: How soon can an a video segment be ready for reading ?

Carl Zwanzig
 > On Fri, Feb 8, 2019 at 4:45 PM Carl Zwanzig<[hidden email]>  wrote:
 >
 >>  and all of it's output

On 2/8/2019 5:01 PM, Subrata Goswami wrote:
> Sure , here is the command.
>
> ffmpeg -y  -i <url> -map 0 -an -sn -dn -r 8/1 -movflags faststart -f
> segment -segment_time 30 -segment_format mp4 -strftime 1/tmp/%d_%s.mp4

Where's the output? (Must have that.)

And please don't top-post here, if you're not sure what that is, please look
it up.

z!


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Re: How soon can an a video segment be ready for reading ?

Subrata Goswami
The output is mentioned above .

mov,mp4,m4a,3gp,3g2,mj2 @ 0x7f1a60002200] moov atom not found



On Fri, Feb 8, 2019 at 5:06 PM Carl Zwanzig <[hidden email]> wrote:

>  > On Fri, Feb 8, 2019 at 4:45 PM Carl Zwanzig<[hidden email]>  wrote:
>  >
>  >>  and all of it's output
>
> On 2/8/2019 5:01 PM, Subrata Goswami wrote:
> > Sure , here is the command.
> >
> > ffmpeg -y  -i <url> -map 0 -an -sn -dn -r 8/1 -movflags faststart -f
> > segment -segment_time 30 -segment_format mp4 -strftime 1/tmp/%d_%s.mp4
>
> Where's the output? (Must have that.)
>
> And please don't top-post here, if you're not sure what that is, please
> look
> it up.
>
> z!
>
>
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> http://ffmpeg.org/mailman/listinfo/ffmpeg-user
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Re: How soon can an a video segment be ready for reading ?

Carl Zwanzig
On 2/8/2019 5:10 PM, Subrata Goswami wrote:
> The output is mentioned above .
> mov,mp4,m4a,3gp,3g2,mj2 @ 0x7f1a60002200] moov atom not found
(no, that's just the error message)

The output _starts_ with something like:
   ffmpeg version 4.1 Copyright (c) 2003-2018 the FFmpeg developers
     built with gcc 8.2.1 (GCC) 20181017

has a lot more lines before (and after) the one containing "moov atom not
found" and ends with the command prompt. Post all of it.

And again, don't top post on this mailing list.

z!
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Re: How soon can an a video segment be ready for reading ?

kumowoon1025
In reply to this post by Subrata Goswami
> On Feb 8, 2019, at 8:01 PM, Subrata Goswami <[hidden email]> wrote:
>
> Trying to read the file  as soon as it is written ( with a simple piece of
> code) throws the following error.
>
> [mov,mp4,m4a,3gp,3g2,mj2 @ 0x7f1a60002200] moov atom not found

When you say “as soon as it is written,” do you mean as soon as the file is opened for writing (when the file appears) or after it’s finished writing and it begins to write the next segment?

In the first case, obviously you will never be able to play back, it’s probably empty.
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Re: How soon can an a video segment be ready for reading ?

Subrata Goswami
On Fri, Feb 8, 2019 at 5:20 PM Ted Park <[hidden email]> wrote:

> > On Feb 8, 2019, at 8:01 PM, Subrata Goswami <[hidden email]> wrote:
> >
> > Trying to read the file  as soon as it is written ( with a simple piece
> of
> > code) throws the following error.
> >
> > [mov,mp4,m4a,3gp,3g2,mj2 @ 0x7f1a60002200] moov atom not found
>
> When you say “as soon as it is written,” do you mean as soon as the file
> is opened for writing (when the file appears) or after it’s finished
> writing and it begins to write the next segment?
>

Write after the file appears in the file system  ( possibly less that 0.5
secs )

>
> In the first case, obviously you will never be able to play back, it’s
> probably empty.
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Re: How soon can an a video segment be ready for reading ?

Carl Zwanzig
On 2/8/2019 5:33 PM, Subrata Goswami wrote:
> Write after the file appears in the file system  ( possibly less that 0.5
> secs )

While the file may appear in the directory, it may not have any data or that
may be incomplete. Also, IIRC setting "faststart" occurs when the file is
being closed, so you'll have to wait for that and for the file system to
flush all of it's buffers.

This also depends on which OS, which file system, storage media, etc.

z!
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Re: How soon can an a video segment be ready for reading ?

Carl Eugen Hoyos-2
In reply to this post by Subrata Goswami
2019-02-09 1:33 GMT+01:00, Subrata Goswami <[hidden email]>:
> Looks like when ffmpeg creates a video  segment, it is not possible
> to start reading that  segment right away.  Throws  "moov atom not
> found" error. So if I have a 30 sec  segment, I have to wait for at
> least 30 secs. Tried the -movflags faststart option,   still throws the
> same error.

(Command line and complete, uncut console output missing.)

What you see is a property of the mov format, not a missing
feature (or bug) in FFmpeg.

Carl Eugen
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