Hitachi HDR253 - why no mention of a severe flaw?

Discussion in 'Digital TV & Video Players & Recorders' started by Pond, Dec 20, 2009.

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  1. Pond

    Pond
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    Since my Topfield 5800 died the other day (after many tweaks and repairs of various magnitude over the years) and since only the awful 5810 could be bought to repair it, I decided to give up on expensive PVRs - just about everything in the market seems fraught with crashes and missed recordings, so why pay lots when they're all junk regardless? Hence I decided to "go budget". Of the various cheapish Vestel clones, the Hitachi HDR253 looked OK so I got one from Argos today.

    It's not too bad really - quite responsive in general, UI is basic but OK, etc.; but there is one major flaw I've not seen in any review: It decodes the picture into the wrong place. The entire TV picture is shifted up by a few lines, so my well-calibrated TV set shows a thin black bar along the bottom edge of the display. Either it's cropping the top edge or compressing the image vertically (but there is no obvious evidence of fractional scaling in terms of picture softness or missing line artefacts).

    Analogue TV, Topfield STB output, PS2 output, LD player and DVD player output is not shifted in this manner. I was similarly horrified when I saw the same thing on a Freeview-decoding Panasonic DVD recorder in another room once, but after a forced OTA firmware update this bug was fixed.

    Call me fussy, but the primary purpose of a TV set-top box is to display TV and the HDR253 doesn't do it properly! Are all Vestel boxes similarly broken? Is it just this Hitachi model? Has nobody else noticed due to overscan, or perhaps because their boxes are actually decoding the image into the correct place on screen and it's just mine that's broken?

    Unless there's a fix for the shifted image decode, I think I'll be forced to return this as unfit for purpose - digital TV receiver cannot correctly receive digital TV. Ho hum! ;)
     
  2. prking

    prking
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    I've never heard of this on a Vestel, either. So I suspect you have a faulty unit.
     
  3. Geofbob

    Geofbob
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    Hi Pond - To answer the direct question you posed - no, all Vestel PVRs are not "broken" in this way. And - hope you don't mind me saying this - it seems something of an over-reaction almost to jump to a conclusion that this might be a general flaw in the Hitachi HDR253, rather than in your particular machine, or in some other feature of your set-up.

    Also, What I find puzzling about this is that you don't relate this to aspect ratio, & seem to expect your screen always to be fully filled. As it happens, I've just watched, via a Vestel PVR, a movie made in 1.85:1 or an even more wide screen format, & of course there were black bands at both top & bottom of the screen. How would I have known if the PVR had been shifting the image slightly upwards? Are quite sure that the aspect ratio settings on both the PVR & TV are properly set?
     
    Last edited: Dec 20, 2009
  4. Futaura

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    Are you using the HDMI or SCART output? Is it not really the case that the position is fine, but the bottom of the picture is being cropped (i.e. missing), and not the top?

    Possibly related to http://pvrbugs.futaura.co.uk/view.php?id=59, maybe (pics are a bit outdated now)? It was a problem on the T810, with a black bar at the bottom of the screen (depending on TV overscan setup), but was fixed for the T816 model, and I'm pretty sure that fix went into the T825 model that you have too. When the fix was made for the T816, I checked the display position against 2 different set top boxes and all were pretty much identical (all 3 varied slightly, so it's impossible to know which exactly what is "correct").
     
  5. Pond

    Pond
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    That's a reasonable assertion, but given that Panasonic managed to have exactly the same kind of fault and fixed it in an OTA update, it wasn't really an overreaction. There are numerous other well-discussed faults in the Vestel clones after all (slowing down EPG, for example). As background to my slightly negative ;) attitude, I've worked as a software engineer in IPTV for over ten years so sadly I'm all too aware of the quality of engineering that often goes into a consumer product these days - it often feels like a race to the bottom which nobody's winning...

    That's because this fault is nothing to do with aspect ratio :) - 1.85:1 movies do not vertically fill the screen (just very nearly) from DVD, Topfield or the Hitachi. The latter ends up with a slightly-bigger-than-its-usual-gap at the bottom. I stumbled across such a movie while channel hopping this afternoon. 16:9 made-for-TV material like Top Gear, OTOH, fills the screen completely on the now-patched Panasonic STB, or the Toppy which is in the mood to work rather than reboot right now (!), but shows a few lines of black at the bottom of the visible region on the Hitachi STB. 4:3 material, too, is shifted on the Hitachi box but not on any other input device I cared to try. FWIW, I've used the "Wide" button on the remote so that the Hitachi device outputs true 4:3 or 16:9 and I let the TV switch, not that it makes any difference to the vertical offset.

    I also note that compared to the Topfield box there is a horizontal compression of one versus the other (there's a significant deviation in the position of objects to the left of the screen but they've almost converged by the right), while the vertical offset looks roughly consistent across the frame but because it's only a few scanlines it's hard to tell by eye (I'm viewing on a CRT in this case, so the picture is some distance "behind" the glass). I'm viewing over RGB SCART, not HDMI, if it makes any difference and for the Topfield/Hitachi comparison used a SCART switcher. Reversing the cable order did not reverse the results so the switcher is not introducing the problem. The horizontal shift is only really visible if you directly compare to another source showing the same material and it's hard to say which is an overall sharper picture horizontally, given Freeview compression rates and a CRT display, without feeding test cards into the boxes somehow.

    In passing I note that the Hitachi decoder employs no smoothing on the chroma channel, so heavily saturated reds are obviously blocky and "stepped" due to the 4:2:0 chroma subsampling in MPEG encoding. The Topfield decoder smooths it, so such issues are a lot less obvious. That's not a fault, it's just a technical difference I see in the implementation.

    Since the offset on the Hitachi is only a few lines it's just the sort of thing that QA and hapless engineers would miss (Panasonic managed it after all). It would easily not be noticed in the home with typical SD "fake" overscan on flat panel TVs or real overscan on CRTs, unless the device was set up via service menus or similar to minimise that overscan (as is the case on my own set). So, I'm very interested in anyone who uses the Hitachi unit over SCART (or HDMI I suppose), knows for sure that their TV is showing them all lines at the bottom edge of the picture and can confirm that their STB definitely fills them correctly.
     
  6. Geofbob

    Geofbob
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    Hi Pond - I can see you've really gone into this, & there does seem to be a problem - though whether it's the HDR253 generally or just yours is still to be determined. Perhaps the best way of finding that out would be for you to exchange your current one for another HDR253, & try that out, rather than just ditching it.
     
  7. Pond

    Pond
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    SCART. Yes, it's possible that this is a cropping/blanking problem rather than a vertical shift. Since there are other position shifts, e.g. horizontally compared with the Topfield, it's hard to be sure which is "right" or "wrong" - only testcards and broadcast monitor or 'scope could be used to determine this with precision.

    That does sound like the right sort of thing. If it's the same bug then we're looking at a reversion of the fault if the 816 had a fix.

    I may try swapping the STB as suggested by another poster. If the new one works properly then great, I just got unlucky and had a bad unit. But if both have the same fault then it's defective by design, shouldn't be on the market yet and it'll go back for good.

    I realise some may be surprised at my reaction, but I think it's only right to take this approach. Being able to correctly decode a TV picture is the most basic and fundamental of things which should be at the very top of the list for a QA department. Whether the device is cheap or expensive, I just can't understand why people hand over their own personal hard-earned cash for things which don't work properly, then seem willing to "forgive" the manufacturer. Is your money and time really worth that little? Manufacturers have a professional, moral and legal responsibility to produce a product fit for purpose; unless they pay me, it isn't my job to test their products for them; and as consumers, we should demand better.

    There. That's my pre-Christmas rant quota filled :thumbsup:
     
  8. Futaura

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    Trouble is, there isn't much choice, especially at the bottom end of the market :(. And bear in mind that manufacturers pay the DTG to test their boxes, so we should really blame the DTG for not bothering about such issues (the amount of bugs that creep through sometimes makes me wonder how some PVRs attain approval from the DTG and the associated Freeview+ accreditation, but that's another story).

    I'm assuming it was a software fix in the T816, but was never able to confirm that. The problem was definitely related to the STM5100 chipset, since I remember at the time, Sagem boxes changed from a PPC based chipset to the STM5100 and magically they started missing lines from the bottom of the picture too. Whether this is the chip or the software (IIRC, Sagem were using the same Cabot middleware that Vestel use) is debatable. There are varitions of the STM5100 chip used - IIRC, my T816 has an STx5100 (think my T810 had a STi5100) - not sure if the differences have anything to do with this issue though.

    Probably the problem may be more noticable over HDMI, with full pixel mapping enabled on the TV (i.e. no overscan), although I guess it depends on whether the PVR does any cropping when upscaling.
     
  9. Pond

    Pond
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    I just didn't want to get into that level of worry when it comes to the STB, so rather than swap the Hitachi for the same thing to see if it was equally problematic, I switched to - and paid £30ish extra for :( - a Humax 9150. Not noticed the fan noise, picture quality is better, it is more responsive, the PiP facilities are good and the pause-live-TV stuff works as I expect (i.e. a continuous buffer, rather than switched off unless Pause is explicitly pressed to activate time shifting).

    I knew that it was spartan - indeed the front panel is dire, just some LEDs and no other display of any kind. It also has no outputs to speak of on the back other than SCART - the cheaper Hitachi had all sorts, even optical out. OTOH it has a hardware on/off rocker switch on the back, a metal earth pin on the plug rather than plastic and a CI slot should I ever want one (unlikely but at least it's there).

    The worst part is the EPG, which is very poor, albeit reasonably quick. It's far too cramped - only 5 channels and almost every programme name is truncated or omitted. Trying to find programmes to record for the forthcoming week is a hopeless task and given that the EPG is the primary interface for this, it makes life difficult. I can't understand why manufacturers don't give the option for a column-style (single channel) guide (I've written both and believe me the column-style guide is a far simpler piece of code). If even Topfield can manage to figure this out, surely other vendors can too! At least Humax do offer a search facility, which should help a bit.

    The rest of the system seems to hang together pretty well so far. I'm now giving it a bunch of recordings to run through to test things out. If the Hitachi had managed to decode video properly (!) then the Humax would look overpriced, but given a few extra features and more responsive UI, guide aside, I think it just about justifies the extra price.

    Thanks to everyone who's responded in this thread.
     
    Last edited: Dec 22, 2009

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