Thanks for your efforts in understanding this problem.
I have some multichannel flac files which play correctly from my laptop sent to my receiver. The same files play to incorrect speakers when using the WD live streamer. I am convinced it is the streamer causing incomparability.
Cheers
muse2u wdsupport@wdc.com wrote:
The more I dig into this, the more I feel like I’m going down a rabbit hole.
I’m inclined to agree with langholm. The FLAC specification at FLAC - Format indicates that the multi-channel implementation follows the recommendation of the SMPTE/ITU-R. The documentation that I have seen from the ITU-R recommends that all implementations of multi-channel media adopt the same channel order and speaker mapping. That mapping is reflected in the FLAC header specification and is identical to the WAV mapping. The fact that the FLAC channel mapping that I have documented above works with the WD live, means that either the WD is not implementing the FLAC decoding properly or my home theater receiver is not decoding the PCM stream properly.
I’m more inclined to believe the former. The WD TV Live is decoding both the WAV file, and decompressing and decoding the FLAC file, to a PCM stream. My receiver is only aware of the PCM stream and not aware of either the WAV file or FLAC file source and would not remap the channels based on the source. I would also assume that if a significant number of WD community members are reporting the same problem, the thing we have in common is the WD and not the receiver. It is highly unlikely that all our different surround sound receivers are mapping the channels wrong. This is also in line with WD customer service agreeing with me a year ago that there was a problem with the firmware interpreting FLAC multi-channel files. As a result of the above posting I have been contacted by WD customer service who again would like to talk to me about my issues. I will do that in the new year and maybe I can get some clarification.
This would suggest that if you have a limited number of multi-channel files, you can remap the FLAC files to the non-standard channel mapping as a work around in order to get the sound out of the correct speakers. Since this is a lossless process, you can always remap them back to the standard format if the firmware ever gets fixed, or you need the files to work with another media player. I would love to hear the experience that anybody has had with the mappings and another media player.
Oneeyedfred, I recommended Audacity as a program to perform the channel remapping and WAV to FLAC conversion because it is a free program, does the remapping and it shows the waveform of each channel. After a little bit of practice it is easy to recognize each of the speaker waveforms. I have not found a way to use it to automate the same procedure on multiple files. dbPoweramp is a commercial program that I would highly recommend to anyone who wants to do audio conversions in a batch mode. It has a channel remap DSP that can be setup to apply a particular remap on many files at the same time. It also uses all the processors in your computer to convert as many files simultaneously as you have processor cores. Excellent program worth the money.
By default dbPoweramp does not remap the channels of an audio file converted from WAV to FLAC. With the version I am familiar with, the channel mapper DSP has to be inserted into the process. I am not sure what you are using as the source of the conversion, a WAV file or using the dbPoweramp ripper to perform a straight conversion to FLAC. If you are not having a problem I would be curious what the source and FLAC channel mappings are.
I have used various programs to convert WAV to FLAC files (including FLAC executable with FLACfrontend) with the same result, they all create the same channel map as the source input; which makes sense if the channel mappings are the same for both formats.
I mentioned the wave extensible format of WAV files in the previous post. Microsoft actually recommends this format be used for multi-channel and high resolution WAV media. This format has a tag that can be used to specify special characteristics of the WAV including a channel bitmap that can remap the physical channel order. Again I don’t know how this applies to a FLAC.
Posted by muse2u on 12/30/2015
