[RESOLVED] How to find an I frame

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laserfan
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Joined: Thu Sep 09, 2010 5:16 pm

[RESOLVED] How to find an I frame

Post by laserfan »

Trying to find I frames in an h264 video. When open it with DGDecNV and step forward from the beginning, the Information window shows the "Playback #"along with the frame type, so it seems in this way I can find the first-many I frames in the video. But if I want to find an I-frame elsewhere e.g. at the end of the video, the only way I can see to do this is to step-thru the whole thing, because if I drag the the location bar along the timeline, the Info changes and counts (apparently) relative to the new setting of the location bar.

Next I looked at the .dgi file, it shows lines with e.g. "I 3952" but I don't understand what the manual is telling me ("an I frame is located at offset n (decimal) in the source file"). Can this "decimal offset" be translated in any way to either a frame number or a time code? I suspect not, since in this case (I 3952) from my actual video according to DGDecNV the next I-frame from the start is at frame 21 which is only 876ms into the video. The "decimal offset" is a memory location then?

If DGDecNV is not the tool for this, does someone an easy way to ID where Iframes are? TIA.
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admin
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Re: How to find an I frame

Post by admin »

Serve the video with DGSource(debug=true) and play it in VirtualDub. It gives the frame type and number.
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laserfan
Posts: 108
Joined: Thu Sep 09, 2010 5:16 pm

Re: How to find an I frame

Post by laserfan »

neuron2 wrote:Serve the video with DGSource(debug=true) and play it in VirtualDub. It gives the frame type and number.
Oh, my goodness; what a wonderful thing. Debug=true where have you been all my life! I love it, thanks. I'd looked in the wrong manual I see--it's described in the DGDecodeNV:
debug=true/false - Enable textual debug overlay on the output video frames. Currently the information displayed is the DGDecodeNV version number, the GOP number, the display and coded frame numbers, and the frame coding type.
Hard to read at my normal window size, but expanding to full screen is fine. Off to change my .avs templates to include this--many thanks! :geek:
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admin
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Re: How to find an I frame

Post by admin »

Thank the guy that suggested it. I just coded it. :lol:

Anyway, glad you find it useful.
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