partial file restore from tape

Previous Topic Next Topic
 
classic Classic list List threaded Threaded
2 messages Options
Reply | Threaded
Open this post in threaded view
|

partial file restore from tape

Swami Kevala
Hi,

We write large HD video files (MXF) to LTO tape. We want to develop a
solution where we can restore a subclip alone from the tape. (This is
commonly referred to as PFR - partial file restore)

I understand the -ss and -t options can be used to cut out a subclip - but
this is only when the entire file is on disk.

Using our tape software we can restore a certain subsection of the file
(based on a byte offset, and byte length). I want to know if we can use
ffmpeg to convert this into a playable file.

I'm guessing we would need some kind of metadata from the original file. So
the kind of thing I'm looking for is a command that will let me copy this
metadata from the file, before I write it to tape (which I would store on
the local disk). I would then want another command which would let me take
this metadata + any extracted byte-stream as inputs and produce a playable
subclip file as output.

Kind Regards

Swami Kevala

--
The information contained in this electronic message and any attachments to
this message are intended for the exclusive use of the addressee(s) and may
contain proprietary, confidential or privileged information. If you are not
the intended recipient, you should not disseminate, distribute or copy this
e-mail. Please notify the sender immediately and destroy all copies of this
message and any attachments. WARNING: Computer viruses can be transmitted
via email. The recipient should check this email and any attachments for
the presence of viruses. The Organisation accepts no liability for any
damage caused by any virus transmitted by this email. www.ishafoundation.org
_______________________________________________
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".
Reply | Threaded
Open this post in threaded view
|

Re: partial file restore from tape

Carl Eugen Hoyos-2
2018-01-08 4:03 GMT+01:00 Swami Kevala <[hidden email]>:

> We write large HD video files (MXF) to LTO tape. We want to develop a
> solution where we can restore a subclip alone from the tape. (This is
> commonly referred to as PFR - partial file restore)

(I wonder if mxf is the original format that you received the files in:
Where they maybe broadcasts in the form of transport streams
before somebody suggested to "archive" them as mxf?)

> I understand the -ss and -t options can be used to cut out a subclip - but

(The options are there to seek and trim but very generally, there
are files where seeking is difficult.)

> this is only when the entire file is on disk.

(I wonder if this is true.)

> Using our tape software we can restore a certain subsection of the file
> (based on a byte offset, and byte length). I want to know if we can use
> ffmpeg to convert this into a playable file.

The question is very general (and we do have mxf samples for which
this would definitely be possible) but I believe in the general sense, you
cannot use FFmpeg to do this, you have to write your own mxf demuxer
that reads the file header and tells your tape software what to get from
the tape. This would not be true if your files were transport streams
(as I wonder they originally were, see above).

I may be missing something and you may only need a new protocol to
access the tape.

[...]

> The information contained in this electronic message and any attachments to
> this message are intended for the exclusive use of the addressee(s) and may
> contain proprietary, confidential or privileged information.

Please remove this from emails sent to a public mailing list.

Carl Eugen
_______________________________________________
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".