Any freeware to determine GOP length?

[Djard]

MediaInfo does not include GOP, and GSpot does not always give the info. Is there any other freeware that can identify GOP length and/or structure (e.g. IBBPBBPBB)?

[poisondeathray]

Some free options:

avisynth, with ffms2 and ffinfo()
ffdshow with osd enabled
ffmpeg or ffprobe to print out list

These first two will show the actual frame preview with the info overlaid

[Djard]

Thanks for responding. I installed ffdshow because I prefer a GUI and let the installation go to the default location, which is a subdirectory of my K-Lite Codec Pack load. I couldn't find an executable file in the ffdshow folder. During installation, I did select VFW as well as VDub, since that is one of my favorite video tools.

I Configured MPC to use ffdshow -> opened a movie -> View -> Video frame, etc. All I could find was MediInfo.

All the screenshots of ffdshow at SourceForge gave me the impression that it was not a command line tool. So how does one use ffdshow to examine GOPs?

[El Heggunte]

Question:

so how does one use ffdshow to examine gops?

Answer:

ffdshow with OSD enabled

[poisondeathray]

To use it in vdub , you would have to configure it so ffdshow vfw is doing the decoding for that specific video. With the video directly loaded , file=>file information will show you what decoder is currently being used. You might have to disable some codecs or configure some vdub internal settings. Yo umight have to use some tools like codec tweak tool, or vcswap

To enable it in ffdshow, under the decoder tab, checkmark osd in the vfw configuration settings, plus what other options you want displayed (frame type, current frame, coded frame size , etc...). The specific codec your video is using has to be enabled as well in ffdshow

Another option is avidemux which will show the frame type

[pandy]

This is difficult for GOP as nowadays especially new codecs with open GOP, long GOP presence may have multiple I frames inside same GOP - In fact you can have long GOP with all frames coded as I frames.