CUDA mpeg2-decode issue (hwaccel)

[barhom]

Summary of the bug:

The new CUDA HW mpeg2 decoder is producing bad and pixelated decoding on some video.
The legacy CUVID mpeg2_cuvid decoder is producing expected output.

The testing has been made with a NVIDIA GTX 1050 Ti GPU with Driver version 440.31 and Cuda 10.2.
FFmpeg version used: git-2019-11-13-a7245ad

How to reproduce:

Bad output:

ffmpeg -y -hwaccel cuda -i "/tmp/original_cut.ts" -c:v h264_nvenc -c:a aac -b:a:0 64k  -f mpegts /tmp/mpeg2_cuda_decode.ts

Good output:

ffmpeg -y -hwaccel cuvid -c:v mpeg2_cuvid -i "/tmp/original_cut.ts" -c:v h264_nvenc -c:a aac -b:a:0 64k  -f mpegts /tmp/mpeg2_cuvid_legacy_decode.ts

I have attached "original_cut.ts" for you to be able to reproduce this issue.
Also attached the output when running the commands on my system.

[barhom]

The good output

[barhom]

The bad output

[Carl Eugen Hoyos]

Which commit introduced the regression?
Please provide the command line you tested together with the complete, uncut console output to make this a valid ticket.

[barhom]

Replying to cehoyos:

Which commit introduced the regression?
Please provide the command line you tested together with the complete, uncut console output to make this a valid ticket.

I cannot say which commit introduced this. Maybe this bug has been here all along.
I attached the uncut console output when using the "bad" CUDA output.

I also tried to use this on todays git commit git-2019-12-26-b0d0d7e.

[barhom]

Console output CUDA

[barhom]

Additional information in case it was not understood:
The encoder makes no difference. You can encode using libx264,h264_nvenc or any other encoder.

The problem arises only from the choice of decoder (before the -i)

[barhom]

Commit d4996a600ca0334235a4b66beae5b5c3474535c4 and 12c4d00c10cb73f1976c8de5b23b1405803bd454 fix this issue.

The patch was posted way back in 2017,
​https://patchwork.ffmpeg.org/project/ffmpeg/patch/20170921032609.26242-1-zhong.li@intel.com/

I guess as discussed in #ffmpeg-devel nobody cared enough about mpeg2-hw decoding.