BD-RB, MKVs, WDTV-Live & Subtitles

[Giljorak]

I have been using BD-RB to create BD25's and BD9's and then convert them to ISO's for a couple of years now. Now that I have setup a Plex Media Server I have started using BD-RB to create MKV's. The main device I use for playback is a WDTV-Live. Either streaming from Plex or playing from a flash drive connected to the WDTV-Live. When playing ISO's from a flashdrive connected to the WDTV-Live the subtitles work fine. Plex doesn't stream ISO's so I can't test those. When I play an MKV file either from the flash drive or streamed from Plex the subtitles do not show up on the screen. When selecting subtitles in WDTV-Live I can see the different subtitle choices but the text does not show up on the screen.

The subtitles work just fine on my PC using Media Player Classic and streaming on my Nexus 7 using the Plex app. They also work fine when playing with MX Player from a usb flash drive mounted to the Nexus 7.

So in an effort to get working subtitles I downloaded an .srt subtitle file for a movie and muxed it into the existing MKV using the mkvmerge GUI. This allowed me to have working subtitles. Here is the kicker, all of the subtitles started working. The ones that didn't work before as well as the new one I just added.

Next, I just opened an existing mkv file in mkvmerge GUI and muxed it straight back out no added subtitles, no changes. This caused the existing subtitles to start working.

I noticed that the version of mkvmerge that is used by mkvmerge GUI is newer than the one that is used by BD-RB so I swapped in the newer version to BD-RB but this did not fix it.

The WDTV-Live has the latest firmware installed, I also tried the latest version of WDLXTV-Live firmware as well, but neither of them worked with mkv's muxed straight out of BD-RB.

I don't know if this is a bug in the WDTV-Live or what so I thought I would put it out there in case someone else runs into the same issue.


Thanks for the awesome software.

[Video Dude]

Seems like WDTV is picky about the subtitle format in mkv. The WDTV can play PGS subtitles in Blu-ray ISO, but for mkv PGS subtitles need to be compressed with zlib. I'm not sure if this is needed for all WDTVs.

http://wdtvforum.com/main/index.php?topic=8640.0

[Giljorak]

Thanks for the thread. MediaInfo confirms that.

Before the remux:
Text #1
ID : 3
Format : PGS
Codec ID : S_HDMV/PGS
Codec ID/Info : The same subtitle format used on BDs/HD-DVDs
Language : English
Default : No
Forced : No

Text #2
ID : 4
Format : PGS
Codec ID : S_HDMV/PGS
Codec ID/Info : The same subtitle format used on BDs/HD-DVDs
Language : English
Default : No
Forced : No


After the remux:
Text #1
ID : 3
Format : PGS
Muxing mode : zlib
Codec ID : S_HDMV/PGS
Codec ID/Info : The same subtitle format used on BDs/HD-DVDs
Language : English
Default : No
Forced : No

Text #2
ID : 4
Format : PGS
Muxing mode : zlib
Codec ID : S_HDMV/PGS
Codec ID/Info : The same subtitle format used on BDs/HD-DVDs
Language : English
Default : No
Forced : No

[soneca]

Seems like WDTV is picky about the subtitle format in mkv. The WDTV can play PGS subtitles in Blu-ray ISO, but for mkv PGS subtitles need to be compressed with zlib. I'm not sure if this is needed for all WDTVs.

http://wdtvforum.com/main/index.php?topic=8640.0

I thought it was a limitation of the chipset Sigma but it seems the WDTV because the WDTV live (Sigma 8670) plays only with the compression and the Dune (Sigma 8642) subtitles work with or without compression. Unless there are differences between these Sigma chipsets ...

[Chetwood]

The compression only applies to PGS subs, embedded VobSubs/SRT are fine without.

[jdobbs]

Unfortunately compressing with zlib can cause issues with some other players. It also causes tsmuxer to fail if you try to use an MKV as a source. I can add a hidden option that let's you enable zlib for subtitles.

Interesting, though, that the player requires zlib and won't accept "none" (used by BD-RB) for the compression. "None" is the only mode that is supposed to be guaranteed to be accepted by all players.

[Giljorak]

I can add a hidden option that let's you enable zlib for subtitles.

That would be awesome, thank you. I look forward to using it.

[soneca]

Thanks jdobbs, this option is really important for those who have media players!!!:rolleyes:

[Chetwood]

Interesting, though, that the player requires zlib and won't accept "none" (used by BD-RB) for the compression. "None" is the only mode that is supposed to be guaranteed to be accepted by all players.
Maybe because it's defined as the default mode in the specs?

[jdobbs]

Maybe because it's defined as the default mode in the specs? Really? It's the default in MKVMERGE but I didn't know it was in the specs as a default. Could you point me to where that is documented? I looked at MATROSKA.ORG and didn't see it. In the MKVMERGE documentation it tells you that "none" is the only mode guaranteed to work on all players -- although it does say that zlib probably is.

[soneca]

The default mode apparently always uses compression.

[jdobbs]

The default mode apparently always uses compression. Is that documented? Standards have to be documented or they aren't standards -- and I can't find it.

[soneca]

jdobbs, i found this information on the mkvmerge documentation.

http://s20.postimg.org/fktmomjrh/zlib1.png

[jdobbs]

Yeah, I already said that it was the default in MKVMERGE a few posts up. But notice the last sentence in your clip. That would lead me to believe that the WDTV is at fault for not supporting "none".

But that's just an application and its documentation -- not the standard. It appears the standard is outlined on MATROSKA.ORG -- but I don't see anything about zlib being the default or a requirement. If I did, I'd make it the default in BD-RB also. As an engineer I'm a firm believer in adhering to standards, without them technology would be nothing but chaos.

[Kurtnoise]

but I don't see anything about zlib being the default or a requirement.
http://matroska.org/technical/specs/index.html

Look at the ContentCompAlgo item...

[soneca]

That would lead me to believe that the WDTV is at fault for not supporting "none".

That's right, should support!

Formerly the WDTV did not support this compression and then went on to support pgs subtitles only compressed for this container.
So a hidden option to disable the option "none" or force zlib option will work the same way, as the zlib is the default unless otherwise specified.

[jdobbs]

http://matroska.org/technical/specs/index.html

Look at the ContentCompAlgo item...Ahhh...I stand corrected. I looked at that column incorrectly. Ok, I'll keep "zlib" on as a default when I create MKVs. The hidden option will be still be added, but only as a means of setting it to "none".

[CV91913]

Ahhh...I stand corrected. I looked at that column incorrectly. Ok, I'll keep "zlib" on as a default when I create MKVs. The hidden option will be still be added, but only as a means of setting it to "none".

I'm not sure if this is a related issue or not. I have been converting a bunch of my movie only bd's to mp4 for viewing on my Android Tab. Your software works great for this. But I ran into an issue with Star Wars Episode 4 - A New Hope...Subtitles. It has 6 English subs. So I used MKV as output. The good news is that all 6 are in the container and MX Player will let me select one (or more) and it displays the sub. The problem is that they don't clear until the next sub appears or 30 seconds or so go by. If you want to test there are a bunch at 50 minutes and 53 minutes. There also seems to be some extraneous sub text that appears at the top of the screen that seem to be part of other sub streams. Don't think these are player issues as I have tried it on a couple of android apps that will display pgs subs with the same results.

[jdobbs]

I'm not sure if this is a related issue or not. I have been converting a bunch of my movie only bd's to mp4 for viewing on my Android Tab. Your software works great for this. But I ran into an issue with Star Wars Episode 4 - A New Hope...Subtitles. It has 6 English subs. So I used MKV as output. The good news is that all 6 are in the container and MX Player will let me select one (or more) and it displays the sub. The problem is that they don't clear until the next sub appears or 30 seconds or so go by. If you want to test there are a bunch at 50 minutes and 53 minutes. There also seems to be some extraneous sub text that appears at the top of the screen that seem to be part of other sub streams. Don't think these are player issues as I have tried it on a couple of android apps that will display pgs subs with the same results.It sure sounds like player issues to me... the subtitles are exactly the same as are included in a BD backup. They're not modified at all, simply included in the MKV mux. The only other possibility would be a bug in MKVMERGE, but I'd consider that unlikely.

[CV91913]

It sure sounds like player issues to me... the subtitles are exactly the same as are included in a BD backup. They're not modified at all, simply included in the MKV mux. The only other possibility would be a bug in MKVMERGE, but I'd consider that unlikely.

You could be right about the players. But I did find this discussion on the mkv forum.

http://www.makemkv.com/forum2/viewtopic.php?f=8&t=4969

I also downloaded the alien dialog only srt version of the subs and they work just fine in the three players I tried. It has been awhile since I did the movie only backup of SW4 but as I recall these subs were a real pain and I had to make multiple trys to get the right one defaulted on.

EDIT...
You, as usual, are right about the players. There are apparently no Android Players (VLC is not compatible with my Samsung Galaxy Tab 3 8.0) that handle PGS subtitles correctly. VLC under Win7 handles the subs just fine. The interesting thing is that there are 6 English subs and Mediainfo says there are 6 PGS streams. But...VLC reports 8 subs with the 7th defaulted on. The same is true for the original BD. I think that is strange but I really don't know how subs are implemented in BD/MKV. As a side note...I was experimenting with trying to get the subs to work in Android and in one of the iterations of test I used mkvmerge to set the default and forced flags on for the 5th sub. When I looked at the result in Mediainfo it said that the subtitle track was PGS zlib where as before it just said PGS. All in all I just think the way that subs were implemented in SW4 was very strange.