Are there any good alternative frontends to XBMC that run under Linux and can be used with TVHeadEnd?

K Shea

XBMC is a great program in many respects, but it has some problems, particularly with its support of PVR backends such as TVHeadEnd. The thought came to me that since XBMC has only had PVR support for the last couple of versions, and since TVHeadEnd has been around a lot longer than that, there must be some other types of frontend software that work with TVHeadEnd. If that's the case, I'd like to know what they are, particularly if any of them have support for NVIDIA VDPAU graphics and Ubuntu Linux.

Three of the problems I have personally encountered with XBMC:

# Picture quality seems "fuzzy"
# Unable to display closed captions from live or recorded TV (this is not the same as downloadable subtitles)

# Unable to play 5.1 sound from live and recorded programs correctly from some sources (left and right surround channels come out of all four left and right speakers!)

Now if I copy a recording from the TVHeadEnd backend and take it to a system that's running MythTV (specifically the Myth frontend) and let it play the recording, then none of these issues appear. The picture is sharp, closed captions can be displayed, and 5.1 sound comes from the correct speakers. However there is a different problem on Myth, in that some recordings simply will not play correctly while others will. I haven't spent enough time experimenting to explain the difference, but on Myth the recording will not play back correctly; the sound or video will stutter, or the playback may fail before the recording ends (I've even seen Myth crash). Play the same recording in XBMC and it plays fine, just with the issues mentioned above. And some recordings will play without issues on either system.

So I got to wondering what other programs people are using to interface with TVHeadEnd. If I understand correctly, unlike MythTV, TVHeadEnd doesn't have its own frontend program, correct?

noggin

For 1 and 3 there are likely to be problems with your XBMC set-up, as XBMC can provide extremely high quality playback of Live TV with 5.1 content (I do this in the UK with both satellite and terrestrial sources) I also have working live broadcast subtitles.

For high-quality pictures you need to ensure you have XBMC configured for the best quality de-interlacing (nVidia GPUs definitely provide the best quality with Temporal/Spatial 2x) If you are watching SD broadcasts in HD you will also need to look at your scaling settings (Lanczos 3 is a good solution if you have the CPU/GPU power for it)

For 5.1 surround audio the solution depends on the broadcasts you are receiving (i.e. whether they use AC3/Dolby Digital 5.1 or AAC 5.1 audio encoding) and whether you are bit streaming (only an option with Dolby/AC3 not with AAC) or decoding to multichannel PCM (an option with both formats)

However you mention Closed Captions. That suggests you are are in a 60Hz (aka NTSC) territory? What is your source of content? DVB-T/T2, -S/S2, -C, ISDB-T or ATSC 8-VSB/QAM?

K Shea

Stephen Neal wrote:
> For 1 and 3 there are likely to be problems with your XBMC set-up, as XBMC can provide extremely high quality playback of Live TV with 5.1 content (I do this in the UK with both satellite and terrestrial sources) I also have working live broadcast subtitles.
>
> For high-quality pictures you need to ensure you have XBMC configured for the best quality de-interlacing (nVidia GPUs definitely provide the best quality with Temporal/Spatial 2x) If you are watching SD broadcasts in HD you will also need to look at your scaling settings (Lanczos 3 is a good solution if you have the CPU/GPU power for it)
>
> For 5.1 surround audio the solution depends on the broadcasts you are receiving (i.e. whether they use AC3/Dolby Digital 5.1 or AAC 5.1 audio encoding) and whether you are bit streaming (only an option with Dolby/AC3 not with AAC) or decoding to multichannel PCM (an option with both formats)
>

> However you mention Closed Captions. That suggests you are are in a 60Hz (aka NTSC) territory? What is your source of content? DVB-T/T2, -S/S2, -C, ISDB-T or ATSC 8-VSB/QAM?

Don't even have the CPU/GPU power for Temporal/Spatial - this is a nVidia ION chipset - but BOB works okay. Most of the time I run with deinterlacing off, it's rarely that noticeable and if I do turn it on it can sometimes cause picture breakups.

3 is not a problem with configuration, it's that XBMC cannot decode certain types of Dolby encoded programming correctly (Pro Logic II I think). My understanding is it uses ffmpeg internally and I know that ffmpeg currently can't decode this format correctly either. MythTV apparently has written their own decoder and it works! To see the problem, if you have a way to d/l YouTube videos, search for "Pro Logic II test" and grab one or two of the test videos that say the names of the channels, and play them in XBMC. Then if you have access to a MythTV frontend, try playing them there. Pay special attention to the rear speakers each time.

Yes I am in NTSC territory, using TVHeadEnd to receive DVB-S/S2.

noggin

Ah.

I'd never really considered ProLogic audio something that would be decoded in XBMC, as Dolby Surround audio is matrix encoded in stereo, and ProLogic is one of the decoding algorithms that are popular (but I believe is patented and proprietary - though you can simulate the Dolby noise reduction and channel steering I guess). (AFAIK the presence or absence of matrix surround is not signalled as being present or not in a stereo audio stream - even broadcasters may not be aware whether the acquired shows they are playing out are encoded for ProLogic decoding). I'd always considered it a function of the AV amp - as it needs to be manually enabled and disabled based on the content you are viewing as you wouldn't want it to be in circuit for regular stereo content - and there is no real way of knowing whether the content is suitable for ProLogic decoding or not. Most movies are - some TV shows were - but XBMC would have no real way of knowing when to switch the matrix decoding in and out I think some DVDs can carry it and flag it (i.e. the audio is compressed as DD2.0 but flagged as having a matrix surround content that triggers AVR ProLogic decoding) but AFAIK broadcasters don't usually run with that level of Metadata integration with their AC3 encoders.

I run with de-interlacing enabled for all Live TV and Recorded TV as I cannot abide de-interlacing artefacts - and much of the content I watch is shot native interlaced (1080/50i or 576/50i) - we don't have any significant 720p broadcasts in the UK. (Though some streaming services are 720/25p) Surprised you are getting picture breakups with de-interlacing though - mine is rock solid on both nVidia and Intel platforms (the Intel stuff is VAAPI decoded with YADIF 2x software de-interlacing - though there are the odd other bugs with Intel / XBMC) Are you running OpenElec or Ubuntu - or Windows?

I've tried MythTV - and it does do a very good job of de-interlacing, but I found the TV Headend + XBMC combo more suitable for my requirements. I use it mainly for DVB-T2 / DVB-S2 viewing of Freeview HD and Freesat HD (MPEG2 576/50i SD, H264 1080/50i HD with a little bit of H264 576/50i SD. Freesat HD uses MP2 and AC3 audio, Freeview HD uses MP2 and AAC audio - both platforms dynamically switch between 2.0 and 5.1 AC3/AAC for HD content with surround) I seldom watch much ProLogic content - but if I can be bothered I enable ProLogic decoding on my amp.

K Shea

Stephen Neal wrote:
> Ah.
>

> I'd never really considered ProLogic audio something that would be decoded in XBMC, as Dolby Surround audio is matrix encoded in stereo, and ProLogic is one of the decoding algorithms that are popular (but I believe is patented and proprietary - though you can simulate the Dolby noise reduction and channel steering I guess). (AFAIK the presence or absence of matrix surround is not signalled as being present or not in a stereo audio stream - even broadcasters may not be aware whether the acquired shows they are playing out are encoded for ProLogic decoding). I'd always considered it a function of the AV amp - as it needs to be manually enabled and disabled based on the content you are viewing as you wouldn't want it to be in circuit for regular stereo content - and there is no real way of knowing whether the content is suitable for ProLogic decoding or not. Most movies are - some TV shows were - but XBMC would have no real way of knowing when to switch the matrix decoding in and out I think some DVDs can carry it and flag it (i.e. the audio is compressed as DD2.0 but flagged as having a matrix surround content that triggers AVR ProLogic decoding) but AFAIK broadcasters don't usually run with that level of Metadata integration with their AC3 encoders.

Well I should clarify that I do not know for sure that this is Pro Logic II, it's just that I read a thread on one of the forums that suggested that was the issue, and the test videos on YouTube play in exactly the same way as the "problem" content, which is to say that audio that should go to the left surround or right surround plays in all four speakers - there is no right/left separation or front/rear separation. But MythTV plays these same test videos and outputs all six channels correctly. Also there was a thread on an ffmpeg forum that said that ffmpeg can encode Pro Logic II but not decode it. They even opened a ticket on it, but so far have not done anything more about it (see http://trac.ffmpeg.org/ticket/4085 ).

> I run with de-interlacing enabled for all Live TV and Recorded TV as I cannot abide de-interlacing artefacts - and much of the content I watch is shot native interlaced (1080/50i or 576/50i) - we don't have any significant 720p broadcasts in the UK. (Though some streaming services are 720/25p) Surprised you are getting picture breakups with de-interlacing though - mine is rock solid on both nVidia and Intel platforms (the Intel stuff is VAAPI decoded with YADIF 2x software de-interlacing - though there are the odd other bugs with Intel / XBMC) Are you running OpenElec or Ubuntu - or Windows?

Ubuntu 12.04 LTS and XBMC Gotham. Don't have Windows, and don't like OpenElec because it takes over the system (you cannot run a desktop or any other programs, except the ones they allow or provide). Regarding "the odd other bugs with Intel / XBMC", can you explain further? I have been thinking about perhaps getting something a little bit more up to date than my current HTPC device, which uses a built-in nVidia ION graphics chipset, but nowadays it seems everything comes with Intel graphics. I understand there is some issue with those that has to do with VAAPI or something, but I don't really understand the issue and don't know how bad the problem really is. And unfortunately, unless I wanted to build a full-blown desktop system (which I don't), I don't see any way to avoid Intel graphics on a low cost HTPC device that will run Linux.

> I've tried MythTV - and it does do a very good job of de-interlacing, but I found the TV Headend + XBMC combo more suitable for my requirements.

Me too.

> I use it mainly for DVB-T2 / DVB-S2 viewing of Freeview HD and Freesat HD (MPEG2 576/50i SD, H264 1080/50i HD with a little bit of H264 576/50i SD. Freesat HD uses MP2 and AC3 audio, Freeview HD uses MP2 and AAC audio - both platforms dynamically switch between 2.0 and 5.1 AC3/AAC for HD content with surround) I seldom watch much ProLogic content - but if I can be bothered I enable ProLogic decoding on my amp.

I think my amp is too old to have ProLogic II - it does have a Dolby setting but that makes no difference with this issue (I normally leave it on THX because I think it sounds better). The connection between the HTPC and the receiver is via SPDIF (optical) and that works very well for movies and such, and for content from a certain group of stations that encode in AC3. The difference is that XBMC recognizes that content as 5.1, whereas on the programs that have the Pro Logic II or whatever it is, XBMC thinks it's 2.0 content (yet still directs output to the left, right, center, and subwoofer correctly). I do have passthough enabled so I'm actually not sure what XBMC does with the sound, all I know is that for whatever reason the MythTV frontend gets the sound right and XBMC doesn't.

FWIW in one of the threads (I think an ffmpeg one) someone said that this is the code that MythTV uses (http://github.com/MythTV/mythtv/blob/master/mythtv/libs/libmythfreesurround/el_processor.cpp) but that they can't just copy it due to some nonsense about different version of open source licenses or something like that. But for all I know, that page could contain coded instructions for baking a cake and I would not know the difference.

noggin

K Shea wrote:

> Well I should clarify that I do not know for sure that this is Pro Logic II, it's just that I read a thread on one of the forums that suggested that was the issue, and the test videos on YouTube play in exactly the same way as the "problem" content, which is to say that audio that should go to the left surround or right surround plays in all four speakers - there is no right/left separation or front/rear separation. But MythTV plays these same test videos and outputs all six channels correctly. Also there was a thread on an ffmpeg forum that said that ffmpeg can encode Pro Logic II but not decode it. They even opened a ticket on it, but so far have not done anything more about it (see http://trac.ffmpeg.org/ticket/4085 ).

To be accurate - ProLogic and ProLogic II are decoding technologies used in amps, they aren't encoding technologies. You don't have material encoded with ProLogic or ProLogic II. Instead I believe the content is encoded with Dolby Stereo or Dolby Surround (not entirely sure the correct description) which is a pretty old way of encoding rear surround (originally just one channel) into a stereo audio signal. It was used in movies as you didn't have to produce additional prints (the audio was compatible with standard stereo kit), but if your cinema paid for a Dolby Surround decoder you got rear channel surround. Then ProLogic was produced as an improved domestic decoding solution - which added things like a centre channel rather than relying on a phantom channel.

It was never really that popular in Europe for TV Production, though movies broadcast on stereo TV channels (our analogue TV system in the UK had a 728kbps 32kHz lightly companded but not compressed digital stereo system called NICAM added in the late 80s) would be ProLogic compatible when broadcast. So decoders had some use over here, and VHS HiFi tracks (and Laseer disc stereo tracks) were similarly compatible.

If you also played conventional stereo that had been well mixed into a ProLogic decoder you found that you got some sound in your rear speakers in ProLogic mode. It might sound quite nice - but it is entirely fake. Decent audience applause mixed with stereo mics will come out of the rear channels for example.

> Ubuntu 12.04 LTS and XBMC Gotham. Don't have Windows, and don't like OpenElec because it takes over the system (you cannot run a desktop or any other programs, except the ones they allow or provide). Regarding "the odd other bugs with Intel / XBMC", can you explain further? I have been thinking about perhaps getting something a little bit more up to date than my current HTPC device, which uses a built-in nVidia ION graphics chipset, but nowadays it seems everything comes with Intel graphics. I understand there is some issue with those that has to do with VAAPI or something, but I don't really understand the issue and don't know how bad the problem really is. And unfortunately, unless I wanted to build a full-blown desktop system (which I don't), I don't see any way to avoid Intel graphics on a low cost HTPC device that will run Linux.

Ah - I run OpenElec mainly - I dedicate my HTPC to OpenElec and "it just works". However there are some Intel driver bugs knocking around that stop it being perfect. Plenty of threads over at forum.kodi.tv about them (kodi being the new name for XBMC). There are issues with Intel's Linux drivers which cause hangs. However if they are fixed the Motion Compensative decoding you get with a Chromebox with a Celeron 2955U Haswell CPU is pretty damn good.

My main HTPC is an i5 with an nVidia GPU in it - and it works brilliantly for pretty much everything. (I have an i5 because I need 4:2:2 decoding of H264 content which isn't VDPAU-friendly) My other HTPCs are ASUS Chromeboxes. They are good - but when the Intel bugs are fixed (fingers crossed) they'll be amazing.

> I think my amp is too old to have ProLogic II - it does have a Dolby setting but that makes no difference with this issue (I normally leave it on THX because I think it sounds better). The connection between the HTPC and the receiver is via SPDIF (optical) and that works very well for movies and such, and for content from a certain group of stations that encode in AC3. The difference is that XBMC recognizes that content as 5.1, whereas on the programs that have the Pro Logic II or whatever it is, XBMC thinks it's 2.0 content (yet still directs output to the left, right, center, and subwoofer correctly). I do have passthough enabled so I'm actually not sure what XBMC does with the sound, all I know is that for whatever reason the MythTV frontend gets the sound right and XBMC doesn't.

ProLogic pre-dates Dolby Digital - it was used with VHS tapes prior to DVD, which introduced Dolby Digital. It may be that your amp is too NEW to support it. It's ancient technology. You do find that some shows made in 5.1 and broadcast with Dolby Digital / AC3 on some platforms have a stereo mix down that creates a ProLogic compatible track (so if you watch them on a stereo channel you get surround with ProLogic) but the quality is average, and the phase relationships required for decent ProLogic decoding can be distured by the MP2/AC3 compression used for broadcast, so results are varied.

That said - all of my Onko amps have still got ProLogic decoding on them. One of them is 6 years old, the other 3 years old. (And these are mainly used HDMI Audio for DTS HD MA, Dolby True HD and multichannel PCM.)

> FWIW in one of the threads (I think an ffmpeg one) someone said that this is the code that MythTV uses (http://github.com/MythTV/mythtv/blob/master/mythtv/libs/libmythfreesurround/el_processor.cpp) but that they can't just copy it due to some nonsense about different version of open source licenses or something like that. But for all I know, that page could contain coded instructions for baking a cake and I would not know the difference.

Licences are really important. They are what run projects like TV Headend, XBMC and allow us to benefit from software that others have worked on and given their work for nothing. I think we have to respect that they can chose to license their code as they wish. I know that there are ongoing discussions about the licences used by TV Headend. Open Source software licences are pretty important.

K Shea

Stephen, thanks for all your comments, there is a lot to think about there. My receiver is an older Onkyo, and it has logos on the front for Dolby Digial, DTS, and THX. However it is old enough that it does not have any kind of HDMI connectivity - there are S-Video connectors on it but I have never used them.

My comment about the license nonsense was because the way I read it, both MythTV and ffmpeg have open source licenses. So one would think that ffmpeg could just use the code from MythTV, but no - apparently the licenses are different in some way (different organizations behind them or something). To me, open source should be open source, if you have a bunch of competing licenses then it makes the software a lot less "open". Anyway that's not my decision to make, but it just a bit frustrating that the way they talk, the answer to how to incorporate Pro Logic II decoding into ffmpeg is right there for anyone to look at in the MythTV code (again, this is what I inferred from what I read, and I have no way to verify), but because of the different licenses they seem to feel they aren't allowed to use it. I hope that sometime in the future (unfortunately probably long after I'm dead and gone) copyrights and patents will disappear completely, because they seem to get in the way of progress so often.