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| videocrack |
| Posted: Feb 9 2013, 11:40 PM |
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Member
Group: Members
Posts: 27
Member No.: 26678
Joined: 27-December 09
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Hello!
the last couple of days I've been trying to find out if it is possible to programatically (C++) seek MPEG-2 videos (recorded on Camcorder DVDs for example) with exact frame-accuracy. With directshow I only managed to seek to keyframes (implemented a seek bar with Display, using IMediaSeeking etc.). I've googled for program examples, asked questions on websites and checked MSDN for useful methods. Latter would always end at an dead-end: ''note [bla bla] does not support frame-accurate seeking.'', except for their newest development:
http://msdn.microsoft.com/en-us/library/wi...v=vs.85%29.aspx
where it says:
| QUOTE | | Seeking. For precise seeking, call the IMFTransform::SetOutputBounds method. When this method is called, the decoder outputs only frames that fall within the range of time stamps specified by the caller. |
however, that only seems to work for the latest Windows platform, Windows 8.
So I'm lost 
The reason why I ask this question here is because the MPEG-2 VirtualDub plugin by fccHandler does the job perfectly. So there obviously is a solution. But how much sense would it make to try and do the same. Is the source code publically available? Is there perhaps a ''simple'' solution that could be implemented with directshow?
Cheers
Stephan |
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| dloneranger |
| Posted: Feb 10 2013, 12:15 PM |
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Moderator
Group: Moderators
Posts: 2366
Member No.: 22158
Joined: 26-September 07
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fcchandlers mpeg2 sourcecode can be found at http://gral.y0.pl/~fcchandler/Plugins/MPEG2/index.html
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MultiAdjust JoinWav WavNormalize FFMPeg Input Plugin v1827 UnSharpMask
Windows7/8 Codec Chooser
All FccHandlers Stuff inc. Installers for acm codecs AAC, AC3, LameMp3 |
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| videocrack |
| Posted: Feb 10 2013, 01:19 PM |
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Member
Group: Members
Posts: 27
Member No.: 26678
Joined: 27-December 09
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thank you dloneranger, I'll have a look at it and try to understand  |
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| phaeron |
| Posted: Feb 16 2013, 07:41 PM |
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Virtualdub Developer
Group: Administrator
Posts: 7773
Member No.: 61
Joined: 30-July 02
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Frame-accurate seeking can be done with MPEG streams but it isn't easy. Whether or not this happens is a quality of implementation issue with the decoder.
There are timestamps scattered throughout the stream, but they're at irregular intervals and there isn't a central index to allow for direct seeking. This means that file scanning is necessary to find the timestamps, after which they must be inferred for following frames. Furthermore, there are a variety of hacks that can be done to MPEG streams that will generally work with players but make frame-accurate seeking more difficult, such as splicing. The only fully reliable way to do it is to pre-scan the entire file. |
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| videocrack |
| Posted: Feb 20 2013, 03:19 PM |
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Member
Group: Members
Posts: 27
Member No.: 26678
Joined: 27-December 09
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| QUOTE (phaeron @ Feb 16 2013, 07:41 PM) | Frame-accurate seeking can be done with MPEG streams but it isn't easy. Whether or not this happens is a quality of implementation issue with the decoder.
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indeed it is, meanwhile I was able to implement it using appropiate codecs. However, I'm stuck again, this time with audio. The odyssey never ends... 
I was able to cut the audio of an AVI file into smaller chunks. But merging them turns out to be a rather difficult task. I guess I'll start another thread for that. If you have some time to take a look at it I'd be glad.
Cheers
Stephan |
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