FFmpeg should support hwaccel to handle device lost issue

[haviet]

I often face "device lost" problem when use hardware-based decoders and I believe others using hardware-based encoders/filters face the same problem.

For example, when the device lost, h264_nvdec (CUDA) decoder would give errors like this:

[h264 @ AVCodecContext] Error decoding a picture with NVDEC: 700
[h264 @ AVCodecContext] hardware accelerator failed to decode picture

There are many reasons may cause GPU device lost during its working such as

• The graphics driver is upgraded.
• The system changes from a power-saving graphics adapter to a performance graphics adapter.
• The graphics device stops responding and is reset.
• User manually disable or enable device.
• A graphics adapter is physically attached or removed.
• Remote access to the PC which could change display resolution.
• Unplugging or plugging the monitor cable to the VGA adapter.
• Etc.

Of course, not all reasons cause "device lost" always, some may happen to some kind of PCs but may not happen to others.

I would FFmpeg to provide a callback mechanism giving the API user a chance to reset or recreate
the hardware acceleration resources, or even switch to software decoder/encoder/filter if the device
can not be recovered.