DLNA improvements - Subtitles, Movie Album Art, Search

[mfulop]

Dear Synology & All,

I am a proud owner of a Synology 209j, together with a PINNACLE media player. All work like a charm, except subtitle support via DLNA. I have to say, I am missing this feature a lot.

I have started to investigate the subtitle issue, and created a debug/development tool, called DLNA Media Browser. This tool lets the user to browse any DLNA compliant media server content, inspect item properties and even dump XML traffic for later investigation.
I used this tool to test Synology, as well as Windows Media Player Sharing on Windows XP, Windows Media Player Sharing on Windows 7, Samsung's PC Share Manager, and TwonkyMedia, to see differences of their DLNA implementations.

The most problematic part is the lack of subtitle (in my case, SRT support) via DLNA. My media player seems not to support SRT subtitles via DLNA in Synology's way, but there's more: due the way Syno handles srt files, the media player gets completely confused and sometimes can not even start the video (I suspect it uses internal indexing which is confused by the srt videoitems).
So far I have not found any standards regarding DLNA vs. subtitles. In fact, everybody does it a different way:
- Windows Media Player Sharing 3.0 and 12.0 (on XP and Win7) seems not so support SRT subtitles at all
- TwonkyMedia introduced their own extensions to handle subtitles. When there is a video file and a related subtitle in the same folder, Twonky only reports the video file, but adds two special attributes (pv:subtitleFileType, pv:subtitleFileUri) to the res element.
- Samsung also introduced their vendor-specific extensions in PC Share Manager (sec:CaptionInfoEx)
- Synology reports the video file and the srt file as two separate files; however both share the same name (title) and only the res ContentType part refers to the mimetype of the object.

You can check screenshots of the tool at http://picasaweb.google.com/miklos.fulop/DLNAMediaBrowser - PM me if you'd like to help with using this tool and dumping XML from various media servers.

I have no idea about how current Media Players handle subtitles via DLNA; but it seems there is no standard way doing this. In a few days, I will also receive a MEDE8ER MED500X and check if some of the above works.

In a nutshell:
(1) Please add configurable subtitle-support for DLNA.

(2) Please add albumArtUri for movies and/or videoItems (when album.jpg, folder.jpg, about.jpg, etc. is found in the same folder as a video).

While I know this is non standard in ContentDirectory.1, there are various media players on the field which support displaying graphics while browsing for a video (see a sample about.jpg in my picasa album on the link above). This would be an easy addition.
albumArtUri for movie:videoItem is already supported and sent by Twonky.

(3) Please add Search capability to the ContentDirectory implementation.
I know this is also an optional feature in ContentDirectory.1 but it would be extremely useful; also WMP and Twonky already support this.

I am interested in your opinions.

[syno.allen]

Hi mfulop:
DSM 2.3 (current in beta stage) has an option to hide the subtitle files from DLNA clients, which might solve the video play problems in a PINNACLE media player.

DSM 2.3 also has an option to edit a list of filenames used as video thumbnails (which was only used in music covers before DSM 2.3).

Could you give us a insight of how the PINNACLE player supports the srt subtitle through UPNP/DLNA such that we can try to support it.

Thanks

[mfulop]

Hi,

that's what I call response time.

Excellent news!! I have already checked DSM 2.3 change log and the demo but found nothing relevant to the Media Server so I have not download it yet. I will test drive DSM 2.3 and see what's changed.

As for Pinnacle subtitles: so far I have not found any ways to display SRT subtitles via DLNA on Pinnacle. I will keep looking, and let you know if I find out something. I am more interested in MEDE8ER MED500X subtitle support. Hopefully it will arrive in a few days and I can check it. Also, Mede8er has some GPL source codes that I can check. I'll post it here.

Many thanks for supporting us - this makes you unique.

[mfulop]

Hi All,

I have continued my little investigation on the subtitles via DLNA topic.

It seems that the most common solution is what D-LINK introduced in their D-LINK DSM media players. These media players automatically try to download the subtitle file whenever a video file is open via DLNA, by simply replacing the res uri extension to .srt.

I have tested D-Link Media Server 1.10, TVersity media player and also checked the source code of MediaTomb. All three media servers behave the same way: say the video res URI is "http://<server>:<port>/web/test_video.avi". In this case, all three media servers handle incoming requests for "http://<server>:<port>/web/test_video.srt" and return the corresponding SRT file, if available. None of them reports the srt file in the library separately.

UPDATE: I just checked my Synology with DSM 2.2 and as I see you are supporting this already. Wow!

PINNACLE: so far I failed to display subtitles on my Showcenter 250HD via DLNA. Even checked with network monitor - the Pinnacle does not automatically request SRTs as above. I will continue looking but I afraid this is a dead end.

MEDE8ER: still on its way to me; in the mean time, I am contacting them to find out which solution they prefer. As Mede8er is (and likely will be) a popular media player, I recommend you to consider supporting them. I will keep posting here as soon as I have new information.

[syno.allen]

Hi mfulop:

Thank for your hard work and insight
Some media players that support both DLNA and Samba will only support subtitles through Samba. (For example, we still cannot find a successful story on WD-TV Live for other Media Servers)

The benefits of DLNA is that it provides an organized menu to access your media files, while Samba only provides folder structure access.

If your coming MEDE8ER supports Samba, you could also try it to see if it support subtitle in this mode.

Thanks

[mfulop]

Mede8er definitely supports samba and subtitles via smb (and nfs).

[mfulop]

The saga continues: Testing DSM 2.3 Media Server...

SUBTITLES:
+ Option 'Hide video subtitles' is very handful. Finally, my Pinnacle is not confused by extra videoItems (still no subtitles though...). Subtitles are correctly returned when specifically asked for, by replacing the .avi extension in the original resource uri to .srt.
* Please add a RES property for such subtitles to videoItems.
Say we have a videoItem with a res of:
<res protocolInfo="http-get:*:video/avi:...">http://<server>:<port>/v/NDLNA/3697.avi</res>
... then add an additional resource to the same object that refers to the default subtitle file:
<res protocolInfo="http-get:*:application/x-srt:...">http://<server>:<port>/v/NDLNA/3697.srt</res>
This would be very useful, especially when 'Hide video subtitles' option is active.

IMAGES:
* Currently Synology only returns two RESs for image items: one thumbnail (JPEG_TN) and one small (JPEG_SM).
This is even true for my 5 megapixels photos. To support high-definition renderers, whenever the source image resolution is big enough, please add resources with JPEG_MED (max 1024x768) and JPEG_LRG (max 4096x4096) quality.

AUDIO THUMBNAILS/ALBUM ART:
+ Music album art was correctly extracted from MP3 tags, or from separate cover.jpg. Embedded image correctly takes precedence over separate album art file.
* upnp:albumArtURI has a dlna:profileID attribute and can be a multiple object. The only currently reported album art for music objects is a JPEG_TN (thumbnail). To support higher resolution media renderers and full screen display of album art, if the available image makes it possible, please also return a JPEG_SM quality albumArtURI.

VIDEO:
! One of my movie files (an .avi) has a reported title 'JUNK'. Why? (It plays normally.)
<item id="45/@2820" parentID="45/3280" restricted="1" xmlns="urn:schemas-upnp-org:metadata-1-0/DIDL-Lite/">
<dc:title xmlns:dc="http://purl.org/dc/elements/1.1/">JUNK</dc:title>
<upnp:class xmlns:upnp="urn:schemas-upnp-org:metadata-1-0/upnp/">object.item.videoItem</upnp:class>
<dc:date xmlns:dc="http://purl.org/dc/elements/1.1/">2010-01-16T19:48:37</dc:date>
<res protocolInfo="http-get:*:video/avi:DLNA.ORG_OP=01;DLNA.ORG_FLAGS=01700000000000000000000000000000" resolution="720x304" size="1953317002" bitrate="262012" duration="02:04:15.000" nrAudioChannels="6" sampleFrequency="48000">http://192.168.77.2:50002/v/NDLNA/2820.avi</res>
<res protocolInfo="http-get:*:image/jpeg:DLNA.ORG_PN=JPEG_TN;DLNA.ORG_FLAGS=00f00000000000000000000000000000">http://192.168.77.2:50002/transcoder/jpegtnscaler.cgi/vfolderart/2820.jpg</res>
</item>

VIDEO THUMBNAILS/ALBUM ART:
! External cover.jpg from movie folder was loaded and reported as thumbnail for video file (as a res element)
* Currently, the only res element for movie folders is JPEG_TN (thumbnail) quality. To support higher resolution media renderers and full screen display of cover, if the available image makes it possible, please also return a JPEG_SM or JPEG_LRG quality. Some media players are able to display full-screen movie information (there are tools which build these overview images, including DVD cover, synopsis, artists and other information).
* While keeping the DLNA-compliant res elements for thumbnails, please also add the same information as upnp:albumArtURI element(s).
* When no external thumbnail file is available, is it possible to extract picture from the video?

GENERAL:
* Is it possible to have different configurations stored by connecting media player? (Say I have two different media players, which require different settings on Synology)

[syno.allen]

Hi mfulop:
If the option "View thumbnails when browsing images through DMA" is checked, please uncheck it to see if it loads original image.

Regarding adding addtional subtitle resource item for VideoItem, has you verified it works for any media player ?

Thanks

[mfulop]

Hi Syno.Allen,

My bad - unchecking this option makes the original image available:

[ ] View thumbnails when browsing images through DMA: JPEG_LRG, JPEG_SM, JPEG_TN
[x] View thumbnails when browsing images through DMA: JPEG_SM, JPEG_TN

Maybe the title of the option is misleading, or at least, not exact. Months ago, I checked this option because I wanted to have thumbnails. The fact is, thumbnails are always there (according to the DLNA guidelines) and this setting only hides the high-resolution resource.

Subtitles as res: not tested, but media players should at least tolerate (and skip) an unknown res element. At the same time, this would be a DLNA-compliant descriptor of a feature that already exists but not advertised (I mean returning the SRT by using the video name).

[mfulop]

I have tested photos via DLNA. For this, I created 13 different jpg images, in different sizes. Then, I checked what kind of resource entries were returned for each image file. I tested the same images on Synology, on Win7 Media Server and on TwonkyMedia (running on Win7). Results here.

* It seems you are restricting JPEG_TN image size for photos to 120x120. However, according to the DLNA guidelines, JPEG_TN's maximum is 160x160 (120x120 applies to JPEG_LRG_ICO). Interestingly, jpegtnscaler.cgi returns images limited to 160x160 pixels for music and video album art.
* For some reason, JPEG_SM size is sometimes restricted to 120x120 (when the original was 1024x1024, 2048x2048 or 4096x4096).
* You do not return JPEG_MED version when JPEG_LRG is available. Imho let the media player decide which one is sufficient for it.
* For extreme big images (over 4096x4096), you do not return JPEG_SM, JPEG_MED and JPEG_LRG version.
* For extreme big images (over 4096x4096), res@protocolInfo's additional info field starts with a ; (protocolInfo="http-get:*:image/jpeg:;DLNA.ORG_OP=01;DLNA.ORG_FLAGS=00f00000000000000000000000000000"). Other media servers simply return * as additionalInfo.

* Regardless of the above, all images were successfully displayed on PINNACLE SHOWCENTER 250HD (but I am not sure about the resolutions used).

[syno.allen]

Subtitles as res: not tested, but media players should at least tolerate (and skip) an unknown res element. At the same time, this would be a DLNA-compliant descriptor of a feature that already exists but not advertised (I mean returning the SRT by using the video name).

We have tried our best to maintain compability with various media players. We need more tests to make sure it won't break other players's compability when adding subtitles as res.

* It seems you are restricting JPEG_TN image size for photos to 120x120. However, according to the DLNA guidelines, JPEG_TN's maximum is 160x160 (120x120 applies to JPEG_LRG_ICO). Interestingly, jpegtnscaler.cgi returns images limited to 160x160 pixels for music and video album art.

This is for historic reason. Photo Station used to generate 120px thumbnail and we want to share it with Media Server. So...

* For extreme big images (over 4096x4096), you do not return JPEG_SM, JPEG_MED and JPEG_LRG version.

DLNA does not specifiy image profile larger than 4096px. We just return original image resource and leave it to decoder.

Your understanding is appreciated.

[mfulop]

Hi Syno.Allen,
"We have tried our best to maintain compability with various media players" - thats very much understandable. You're right, the key is to have subtitles working.
120px thumbnails: I think we can live with them; also extreme big pictures are a rare use case. I understand.

[mfulop]

Hi,

Any comments on adding "Search" to DLNA?

Thanks!

[peterk]

Subtitles as res: not tested, but media players should at least tolerate (and skip) an unknown res element. At the same time, this would be a DLNA-compliant descriptor of a feature that already exists but not advertised (I mean returning the SRT by using the video name).

We have tried our best to maintain compability with various media players. We need more tests to make sure it won't break other players's compability when adding subtitles as res.

Could this be configurable maybe?

[syno.allen]

Hi,

Any comments on adding "Search" to DLNA?

Thanks!

This is being planning but I cannot guarantee when we will finish the implementation.