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AVI turns to MKV in copy mode

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HMR:
Hello everyone,
I suspect my question is lame but I'll still ask since my video formats knowledge is lame too.
I try to cut a piece from AVI file.
Use A/B markers, COPY option for both video and audio, save as.
But, I can only save to .mkv format, and get MKV file as a result.
Is it "uncompressed cut"? I don't want my videos to be re-encoded, just want a clear copy, with NO compression.
I thought output file format has to be same, in such case. AVI to AVI, MKV to MKV etc.
But this format difference at the end confuses me.
Some help/explanation would really help.
Thanks!!!

zakk:

--- Quote from: HMR on January 06, 2018, 03:10:25 PM ---I can only save to .mkv format

--- End quote ---
What do you mean ?

eumagga0x2a:

--- Quote from: HMR on January 06, 2018, 03:10:25 PM ---I can only save to .mkv format, and get MKV file as a result.
--- End quote ---

Sure you can change the default output container to something else, but MKV is just the best choice. MP4 is actually even better for some purposes (exact timing while MKV is limited to 1 millisecond accuracy), but much less flexible.


--- Quote ---Is it "uncompressed cut"? I don't want my videos to be re-encoded, just want a clear copy, with NO compression.
--- End quote ---

Most likely your videos are already compressed, otherwise they would easily occupy hundreds of gigabytes worth of disk space. Leaving the video and audio codec at the default setting "copy" means that compressed video and audio frames will be written to the output container without being first decoded and then reencoded – exactly as you wish.


--- Quote ---I thought output file format has to be same, in such case. AVI to AVI, MKV to MKV etc.
--- End quote ---

No, not at all. A container is just a structure to explain where the actual frames are stored. However, some containers impose limitations on codecs used to compress audio and video as well as on other features (e.g. MKV allows to store subtitles and supports also chapters, and the chapters may overlap if needed). AVI is a legacy container whose shortcomings make it incompatible with modern codecs. Avoid saving video as AVI as good as you can.

GeoSlv:
I also have avi editors in Windows so dropping avi support is a big letdown. Go to filehippo and get older versions. I haven't checked v.6.
Why should we be so gung-ho on x264 when it has so fewer editing capabilities, like no cutting between key frames. Is that "I frame"? Is that called Index?

eumagga0x2a:

--- Quote from: GeoSlv on January 28, 2018, 10:28:56 PM ---I also have avi editors in Windows so dropping avi support is a big letdown.
--- End quote ---

No one plans to drop AVI support in Avidemux. What gives you that idea?


--- Quote ---Why should we be so gung-ho on x264
--- End quote ---

Excellent visual quality at high compression rates. But HEVC is even better.


--- Quote ---when it has so fewer editing capabilities, like no cutting between key frames.
--- End quote ---

No codec in the world allows to place the entry point in copy mode not at a keyframe (more precisely, not at an IDR frame) without more or less severe video corruption. The exit point may be at a P-frame as far as no previous B-frame uses a later frame as reference. Success is guaranteed only when cutting at an IDR frame (also called keyframe or I-frame = intra coded frame). This limitation is pure maths, not an evil conspiracy :-)

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