--tiles 1 --speed 1 produces lower quality nearly same filesize output than --tiles 8 --speed 3 with same quantizer
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Description
The input file was the following: http://fratti.ch/mediasamples/chansu.y4m
Sample A was encoded with --tiles 8 --speed 3 --quantizer 150: https://fratti.ch/mediasamples/chansu_slow.ivf
Sample B was encoded with --tiles 1 --speed 1 --quantizer 150: https://fratti.ch/mediasamples/chansu_slower.ivf
As one can see, sample B took longer to encode (duh), looks worse in several places that I could find, and is larger than about the same size as sample A.
My expectation is that the encoder being allowed to use slower algorithms and look at the entire frame should produce higher quality or lower filesize output at the same quantizer level.
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
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- Open a pull request that references the issue number.
Research direction
Reproduce the report using chansu.y4m and the two command lines, then compare encoded quality, filesize, and runtime for the linked IVF samples. Determine whether the slower single-tile configuration is expected to improve results; done means the behavior is explained or corrected and the comparison is covered by an appropriate regression check.
Written by the indexing model from the issue text.
Assessment
- Domain
- performance
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100