It's not clear to me what the best setting to export a video project as lossless stills

A lot of error messages came through over the last day when trying to export as stills: a 150 minute video The job doesn’t finish, and it didn’t even say failed, but it got closer (63 percent) to completing when I keep other running programs off. How do I export them without it stopping, is it just that I was using a crap computer, or are my export settings wrong… I’m basically wondering if there’s any point in as a member in the forum suggestd: using advanced export settings to put the resolution to 1080 x 1080 (some of the vdeio in this comp is 1080, but not higher) and aspect ratio 1 - 1, and the stills were set to png. I also had the export settings at 100 percent quality. I would like to know what of that is going to make a difference how good the stills are. Maybe I was making the would-be restulting file bigger than it needs to be in order to keep the stills as lossless as possible.

Since the frame rate of the project is not specified, I’m going to use 24fps as an example.

If the project is 150 minutes long, then exporting as stills will create 150 min * 60 sec/min * 24 frames/sec = 216,000 PNG files.

However, Shotcut only adds a 5-digit frame counter to the end of an exported image file by default. Since there are more frames than the image counter can represent, a rollover will happen and Shotcut will probably halt due to “file whatever-00000.png already exists and I’m not going to overwrite it”.

Try exporting again, but add %06d somewhere in your filename to embed a 6-digit frame counter. An example: MyBigLongMovie-%06d.png which Shotcut will then export as MyBigLongMovie-000001-00001.png because it contains both your custom 6-digit counter and the default 5-digit counter. The 6-digit counter will keep the filename unique after the 99,999th frame.

This is a guess regarding the export error. The real way to know is right-click the failed job and choose “View Log”, and see what broke.

This sounds scary. If the timeline is not 1080x1080 or some other form of square, then there will be squish problems.

If computer hardware is a concern, then reboot, close all possible auto-start programs, start Shotcut, don’t even hit play to preview, and go straight to export. This will give Shotcut the most RAM possible for export.

The Shotcut timeline is YUV 4:2:2 limited range (assuming you didn’t add mlt_image_format to the Other tab). PNG files are RGB 4:4:4 full range. Some degree of loss is going to happen in conversion, albeit negligible. Are stills a project requirement? H.264 Lossless video wouldn’t be an option?

MLT (the Shotcut engine) automatically changes the mlt_image_format (if not explicitly stated) to an RGB(A) one if the encoder’s default pixel format is RGB(A).

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Good to know, thanks.

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