Want all I-frames in Video, no B and P frames

[gumby]

How do I set Avidemux 2.6.4 so that the MP4-AVC x264 video that I encode will have only I-frames and nothing but I-frames. (To enable future lossless keyframe edits)

Alternatively, for some vids I'd like to have an I-frame every half second or every second. How would I adjust the settings to do that?

Where do you set this? In x264 configuration? GOP Size? I-Frame Threshold? What values should I enter?

This advanced configuration stuff is way over my head. I just want an easy way to make sure that the I-frames are spaced very close to each other, not far apart, to make editing more precise.

Thanks for any help.

[tuxutat]

You're looking for the GOP size settings. Minimum / Maximum = min/max amount of frames till the next keyframe, so setting Max to 1 will give you only keyframes.

The file size will be really large, though.

[AQUAR]

I wonder if h264 with only intra frames is really the best way to obtain an editable video with lossless compression?
There are interesting I frame only lossless compressors available eg FFV1 and if coupled with the "old" frame based avidemux it might just be the ticket. Should at least be worth a comparison test. 

[gumby]

You're looking for the GOP size settings. Minimum / Maximum = min/max amount of frames till the next keyframe, so setting Max to 1 will give you only keyframes.

The file size will be really large, though.

Thanks Tuxutat. What about the I-Frame threshold setting? What do I do with that?

[gumby]

I wonder if h264 with only intra frames is really the best way to obtain an editable video with lossless compression?
There are interesting I frame only lossless compressors available eg FFV1 and if coupled with the "old" frame based avidemux it might just be the ticket. Should at least be worth a comparison test.

Thanks for the suggestion, Aquar. I will google FFV1 and try to find out more.

I do find that this newest version of Avidemux is the first one that really works at editing FLVs, especially .264s. I used to have many problems with the older versions.

[tuxutat]

Thanks Tuxutat. What about the I-Frame threshold setting? What do I do with that?

It's for scene change / cut detection. A value of 10 to 20 will detect pretty much all scene changes and place a keyframe at the beginning (if Min is low enough), but might place too many in fast action scenes.

I personally sometimes encode videos without heavy action with Min/Max/Threshold = 1/50/10 to make them more editable later. This will place a keyframe every 2 seconds (for 25fps video) and at every camera cut. It's a good trade-off with respect to file size, only around 10-15% larger files in CRF mode on average compared to default settings if I remember correctly.

[AQUAR]

@ tuxutat
Yes, its a good step forward for this type of compressed video.
The older version also works fine if you preprocess first with avisynth.

[gumby]

Thanks Tuxutat. What about the I-Frame threshold setting? What do I do with that?

It's for scene change / cut detection. A value of 10 to 20 will detect pretty much all scene changes and place a keyframe at the beginning (if Min is low enough), but might place too many in fast action scenes.

I personally sometimes encode videos without heavy action with Min/Max/Threshold = 1/50/10 to make them more editable later. This will place a keyframe every 2 seconds (for 25fps video) and at every camera cut. It's a good trade-off with respect to file size, only around 10-15% larger files in CRF mode on average compared to default settings if I remember correctly.

Thanks Tuxutat. I'll try your settings.