My friend somehow managed to get a BDP-95, even though the hardware isn't scheduled to ship until March. The problem is that the manual makes no mention of FLAC, at all, and only the web page claims to support the format. Playback of flac seems to work, but files from one online vendor work flawlessly while files from other online vendors have strange glitches that sound like a chirp or some kind of cheesy sci-fi movie laser effect. My hunch is that the flac files with problems were possibly compressed with --best or -8 and are just too much for the BDP-95 to keep up with. Considering that the oppo BDP-95 supports 192 kHz playback and surround, I would expect them to use a fast processor that can keep up with the demands of flac decoding. Perhaps these problems will be fixed in the future with a firmware upgrade - at least I hope it's not a situation where the processor is simply underpowered and no amount of firmware rewriting will work. I tried to browse around the main flac site looking for information about hardware decoders, but I could not find any details. Has anyone documented the levels of support for various pieces of hardware? Actually, I see that the Squeezebox and Transporter are specifically documented as supporting flac compression levels 0 through 8, which is great. Is there similar documentation of other hardware platforms? I guess the BDP-95 is too new to be on any such list anyway, but I was hoping to see more than three devices with these details. If anyone has suggestions, please let me know. I tried a couple of Google searches, as well as Bing, but that was probably redundant. Maybe I didn't use the right key words. I'm suggesting that my friend uncompress to WAV and then recompress with flac --fast, but I'm wondering if there is an easy way to know that I higher level of compression would be guaranteed to work, even for 'slow' hardware decoders. Brian Willoughby Sound Consulting
Correct me if wrong, but I was under the impression that the processing required for playback was totally independent on the level of compression. The encoder looks for polynomials that fit, and it takes much more processing to find polynomials with a very good fit and small residuals. On the other hand, the decoder just has to multiply out the stored prediction, which is independent of the compression level. Nicholas ----- Nicholas Wilson: nicholas at nicholaswilson.me.uk (ncw33) Site and blog: www.nicholaswilson.me.uk Peterhouse, CB2 1RD ? 86 Heath Road, GU31 4EL On 5 February 2011 23:15, Brian Willoughby <brianw at sounds.wa.com> wrote:> My friend somehow managed to get a BDP-95, even though the hardware > isn't scheduled to ship until March. The problem is that the manual > makes no mention of FLAC, at all, and only the web page claims to > support the format. > > Playback of flac seems to work, but files from one online vendor work > flawlessly while files from other online vendors have strange > glitches that sound like a chirp or some kind of cheesy sci-fi movie > laser effect. My hunch is that the flac files with problems were > possibly compressed with --best or -8 and are just too much for the > BDP-95 to keep up with. Considering that the oppo BDP-95 supports > 192 kHz playback and surround, I would expect them to use a fast > processor that can keep up with the demands of flac decoding. > Perhaps these problems will be fixed in the future with a firmware > upgrade - at least I hope it's not a situation where the processor is > simply underpowered and no amount of firmware rewriting will work. > > I tried to browse around the main flac site looking for information > about hardware decoders, but I could not find any details. Has > anyone documented the levels of support for various pieces of > hardware? Actually, I see that the Squeezebox and Transporter are > specifically documented as supporting flac compression levels 0 > through 8, which is great. Is there similar documentation of other > hardware platforms? I guess the BDP-95 is too new to be on any such > list anyway, but I was hoping to see more than three devices with > these details. > > If anyone has suggestions, please let me know. I tried a couple of > Google searches, as well as Bing, but that was probably redundant. > Maybe I didn't use the right key words. > > I'm suggesting that my friend uncompress to WAV and then recompress > with flac --fast, but I'm wondering if there is an easy way to know > that I higher level of compression would be guaranteed to work, even > for 'slow' hardware decoders. > > Brian Willoughby > Sound Consulting > > _______________________________________________ > Flac mailing list > Flac at xiph.org > http://lists.xiph.org/mailman/listinfo/flac >-------------- next part -------------- An HTML attachment was scrubbed... URL: http://lists.xiph.org/pipermail/flac/attachments/20110206/e57783b7/attachment.htm
Thanks for bringing up this aspect, Nicholas. I seem to recall that specific hardware has a problem with certain compression levels, but I cannot recall whether that was limited to just encoding, or decoding as well. It could very well be true that I am conflating my vague memory of encoder limitations with decoder limitations. It does seem to be that the oppo BDP-95 is exhibiting problems with particular flac files. Since my original message, my friend has installed the latest version of flac and recompressed the exact files that were giving him a problem before - now with -0 or --fast he doesn't see a playback problem at all. So, even though your statements make total sense to me, the evidence seems to indicate something about the compressed data that's causing a problem. The original audio is not the issue, but how it is compressed. Here's a thought: Since the encoder looks for polynomials, could it be possible that certain decoders cannot handle certain polynomials in real time? Ah, another possibility is that the oppo BDP-95 implements an older version of the decoder, and it's merely new flac files that give it a headache. My friend happened to have an old version of flac installed on his computer, 1.1.4, and that reported stream errors with his files until he upgraded to 1.2.1 - if the oppo has anything older than 1.2.1 then I suppose that might explain the decoding problems. Brian On Feb 5, 2011, at 16:33, Nicholas Wilson wrote:> Correct me if wrong, but I was under the impression that the > processing required for playback was totally independent on the > level of compression. The encoder looks for polynomials that fit, > and it takes much more processing to find polynomials with a very > good fit and small residuals. On the other hand, the decoder just > has to multiply out the stored prediction, which is independent of > the compression level. > > Nicholas