Convert to MP4 doesn't support resolution changes

[obilodeau]

Preconditions during the MITM session:

• client connects to a low resolution
• client updates to a higher resolution (tested: via client dynamic resolution update, not tested: via manual resolution change)

Converting this .pyrdp file to an MP4 will result in a video that uses the first low resolution throughout the duration of the video meaning you will miss out on some screen elements.

Attaching a capture to repro the issue.

[obilodeau]

reproducer.zip

[alxbl]

This is tricky, AFAIK H264 doesn't support dynamic resolution changes within the same stream. I can think of two approaches:

1. Do a first passs of the replay to look for resolution changes and use the maximum resolution. Fit everything else (resize or pad with borders?) into the frame
2. Finalize the mp4 and start a new render. Maybe with extra info in the title

Approach 2 seems like the easiest to implement, but not the most user-friendly.

I'll take a look at the dynamic resolution handling code and see if I can handle it in the Mp4Handler to implement approach 2

[obilodeau]

I think option 1) is the only option. Especially if one would create a conversion pipeline. Creating a new file would be surprising and hard to track.

Then again, how fast is this first pass going to be? I hope it'll be fast.

An interim fix would be to emit a warning and exit with a non-zero status if there's a resolution change in a conversion. That would send a clear message to users.

[alxbl]

I do not know how heavy it will be to parse the whole session without actually rendering it. ~If you have a repro capture, you can send it to me off-band, otherwise I'll try to prepare one myself.~ I see you attached the files above... D:

client updates to a higher resolution (tested: via client dynamic resolution update, not tested: via manual resolution change)

This isn't allowed by MSTSC as far as I know. Maybe some Linux clients allow it, though?