Reinitialize cdm video decoder only when codec change

[CastagnaIT]

OpenVideoDecoder is called each time that the stream quality change and currently force call InitializeVideoDecoder in the cdm during playback, at least with N@tflix this cause cdm errors when the stream quality is switched during the playback, so freeze the playback

A possible solution is call DeinitializeDecoder before recall InitializeVideoDecoder,
but as is implemented now cause a delay (image freezed for some secs),

from a search on chromium sources seem that they allow call InitializeVideoDecoder
during playback, but only in the situation that the codec change,
trying to do this i can see that the playback now works when stream quality change,
we will see if someone report a regression but it should not

Since i compared the sources, i took the opportunity to do some cleaning, and to make some parts more similar to chromium conterpart. Changes:

• DecodeVideo method is now splitted in to: DecryptAndDecodeVideo, VideoFrameDataToPicture
• Moved host global variable to new Helper.h, to allow have access to log methods without being restricted by each class (in a future prospective to have the main/ssd projects merged)
• Add cdm_type_conversions.h (adapted from chromium sources) to contains all cdm data type conversions
• Removed unnecessary reallocations and member variables in WV_CencSingleSampleDecrypter in favour of simple vectors
• Implemented all fields in SSD_SAMPLE struct, to have full DEMUX_PACKET crypto data

The only functional change in the cleanup is that the cdm::InputBuffer_2 cdm_in; defined in to previous DecodeVideo method
is now constructed by using all info of SSD_SAMPLE (DEMUX_PACKET) data, instead of take some info from members variables like m_CryptBlocks, m_SkipBlocks, m_EncryptionScheme

WIP: not done android side cleanups

[glennguy]

Amazing, looks really good!

[glennguy]

So does this then solve the issue we would have on amlogic/CE devices where video is lost after the first stream change?

[CastagnaIT]

yes tested (with n@tflix) on CoreElec when DEMUX_SPECIALID is signaled not stuck the playback anymore,
although not yet perfect, the quality switching:
-with H264, works but frames seem to be mixed for 1-2 secs, after that playback continues as normal
-with VP9, no problems, as usual the little black screen transition only

comparing to Windows build, the quality switching:
-with H264, works but transition can freeze image for 1 sec, after that playback continues as normal
-with VP9, no problems, transition looks smooth without black screen transition

[glennguy]

Great! It's certainly better than no picture at all. Maybe some improvements on Kodi side can make it more seamless.