The lip-sync problem in digital television: a demonstration and solution

Do you find on your TV that people’s lips move after you have heard the words spoken? This is the lip-sync problem. There are several causes, and several solutions. The video demonstrates the lip sync problem and presents a solution based on using a modestly-priced little brown box.

First, I present several experiments that demonstrate the lip sync problem. Next, I show the solution I implemented and several confirmation checks. After the demonstration I explain why the solution achieves its results.
Watch the demonstration lipsync error video on YouTube here: http://www.youtube.com/watch?v=LTgC4J3UPgs

To conduct the experiments, I replay the same piece of video material from a digital video recorder (MySky HD) to the television (Samsung LED) and stereo amplifier system (Denon 500 PMA). A series of figures shows the equipment set-up for each demonstration. I located a home video camera in front of the TV to record what I saw and what I heard. The video image is not great! However, the video image is sufficient to observe the lip sync problem and the effectiveness of the solution.

Explanation
Why does the solution work? The modern digital TV requires around 50 - 200 milliseconds to process the digital data it receives from a signal source, and display the image on the LED screen. There are many reasons for this delay. (See LCD Input Lag / Video Delay measurement ) The traditional analogue TV appears not to have possessed this delay ‘feature’ to a level that is noticeable. Furthermore, the higher quality image, and/or larger size of modern TVs renders the problem more apparent.

Consequently,  if you route the sound output from your signal source - such as a digital video recorder - to your hi-fi stereo amplifier system, you hear the sound BEFORE the digital TV has processed and presented the image. 200 milliseconds is ⅕ th of a second. That is a very small time period. However, the problem it caused was noticeable immediately to me when I upgraded from our 1980s vintage television earlier this year to a Samsung LED TV. You will see and hear the delay in the demonstration video, Experiments 1, and 2.

Fortunately, my Samsung digital TV provides an optical digital audio output that appears to be synchronized closely with the delayed TV image. Consequently, to solve the problem, you must take the digital audio signal output from the TV into your hi-fi stereo system. I credit the MySky technician who installed the MySky High Definition digital recorder for that solution strategy. Experiment 3 shows how the audio signal broadcast from the TV is more closely synchronized with the video image … However, the sound quality is rather unacceptable since it is produced from small 2 x 10 Watt speakers in the TV, rather than my 2 x 130 Watt Denon hi-fi with KEF speakers!

My hi-fi is a classic 1980s vintage Denon 500 PMA hi-fi amplifier. Consequently, the Denon amp accepts only analogue audio input, via RCA cables. Rather than purchase a new digital surround-sound hi-fi system, I wished to retain this vintage legacy system for several reasons. The Denon is not broken. It sound great. Furthermore, it provides a key component of the method I use to converting my vinyl LP collection into a digital format via a Zoom H4n Digital Recorder - but that’s another story.

To the rescue comes a little brown box that converts digital audio signals to analogue signals. In my case, I purchased an AC1603 Coaxial/Optical to R/L audio converter sourced via TradeMe, but ultimately supplied by Electus Distribution Pty Ltd, NSW Australia, http://www.electusdistribution.com.au. You also require a digital optical cable and an RCA Right and Left channel cable, male-male connectors.
Connect the audio converter between the TV and your hi-fi system.  The video segment ‘Solution’ demonstrates the functioning of the digital-audio converter, and shows better synchronization between what you see (the lips) and hear. The ‘Check’ demonstration shows sound broadcast through both the TV and hi-fi. There is a much reduced, but acceptable delay between the two sound sources.
 Image via Wikipedia
A comprehensive solution
Once you have this system installed, you should reroute your DVD and other audio-video signals first to the TV rather than through your hi-fi system. You must route BOTH the audio and video signals to the TV, so that the audio signal is relayed back to your hi-fi system. You will then achieve better synchronization of audio and video from these additional sources when you play the sound through your hi-fi system.

This set-up enabled me to connect an AppleTV. This little black box connects via digital HDMI cable to the TV, and behaves like an additional audio-visual input. Now I can surf on my TV Youtube and Flickr from the comfort of my couch, listen in highest hi-fi to my iTunes music collection, and view in brilliant colour the photo albums stored on my computer. The AppleTV is a pure digital device. It connects only to your TV via a HDMI cable. Without the setup I describe above, I would not have been able to use the AppleTV through my hi-fi system, which would defeat much of the purpose of the AppleTV box for relaying the iTunes collection to the hi-fi.

Costs
Coaxial/Optical Digital to R/L audio converter $NZ 84.50 including courier postage $5.00.
Digital optical cable, 2 metre, $NZ 25 including courier postage $5.00
Total: $NZ 110
If you are not so fortunate with TradeMe, you can order a solution from Australia with total cost about $150. Try http://www.converters.tv/

Technical note
We assume that there is perfect synchronization between the video and audio image recorded on the video camera. We also assume that there are no losses in synchronization during the creation of the movie from iMovie, the upload and processing by YouTube, and your viewing of the video over the internet! The demonstration works satisfactorily on my computer!
I may have been slightly hyperbolic about my estimate of my TV’s video processing delay I estimated 200 milliseconds. The point is, I notice the delay, and some readers/viewers will also notice the delay. Apparently, some people can notice a delay of 40 milliseconds. Various hobbyists and gamers measure and publish the delay and a report from Stanford University report on how the delay affects peoples’ perceptions of the message presented. See Reeves & Voelker (1993), LCD HDTV Input Lag Tests, and LCD Input Lag / Video Delay measurement, (below).

IMPORTANT NOTE
I have viewed the lip-sync video on YouTube. If you watch it whilst downloading, you get lip-sync failure throughout the whole video! Wait for the video to download before playing it!


Equipment used

• Television: Samsung LED TV UA32.B6000, 32 inch(!), 2 x 10 Watt, 1920 x 1080 @ 60 Hz
• Digital recorder: MySky HDi
• HiFi amplifier: Denon PMA-500V 2 x 130 Watt
• Digital-analogue converter: AC1603 Coaxial/Optical to R/L audio converter
• Video camera: Panasonic 3CCD PV-GS150
• Microphone: Zoom H4n Handy Recorder

Further reading
Delay measurement and effects
LCD Input Lag / Video Delay measurement (PC & console games responsiveness) - AVForums.com. (n.d.). Retrieved November 4, 2010, from http://www.avforums.com/forums/lcd-led-lcd-tvs/612503-lcd-input-lag-video-delay-measurement-pc-console-games-responsiveness.html
LCD HDTV Input Lag Tests. (2008, September 8). ARogan. Retrieved November 18, 2010, from http://blog.arogan.com/2008/09/lcd-hdtv-input-lag-tests.html
Reeves, B., & Voelker, D. (1993, October). Effects of Audio-Video Asynchrony on Viewer’s Memory, Evaluation of Content and Detection Ability - Research Report Prepared for 
Pixel Instruments. Stanford University. Retrieved 18 November, 2010, from http://www.lipfix.com/file/doc/stanfordresearch.pdf

More advanced solutions: Audio delay boxes
In some cases the miss-match between audio and video signal originates in the source signals. For instance, DVD audio tracks may be out of sync with the video track. In these cases, more sophisticated solutions are available. An audio delay box can be used to match the audio and video signals whatever and whenever the source is transmitted.

These are rather more expensive solutions. For example, see
AD-100 Audio Delay Box. (n.d.). Retrieved November 4, 2010, from http://www.datavideo.us/products/tbcs-and-audio-delay/ad-100-audio-delay-box.html
Lip-Sync Error Technical Details. (n.d.). . Retrieved November 18, 2010, from http://www.lipfix.com/technical_details.html
Lip-Sync Error? Felston DD740. (n.d.). . Retrieved November 4, 2010, from http://www.lipfix.com/lip_sync_error.html
Lip Sync Error Fix. Digital Audio Delay - Plasma TV, LCD, DLP - Felston. (n.d.).  Retrieved November 4, 2010, from http://www.felston.com/
An intermediate-price solution uses a standard digital audio effects processor. Not quite so user-friendly to use as the Felston approach.
Possible cheap lip sync solution (for non lip sync equipped AV amps) - AVForums.com. (n.d.).  Retrieved November 4, 2010, from http://www.avforums.com/forums/av-amplifiers-receivers/379273-possible-cheap-lip-sync-solution-non-lip-sync-equipped-av-amps.html
BEHRINGER: FEX800. (n.d.). Retrieved November 4, 2010, from http://www.behringer.com/EN/Products/FEX800.aspx

Digital to analogue audio converters
HDTV, DVI, HDMI, VGA, PAL, NTSC, CGA, EGA, RGB Video Scan Converters Sales. (n.d.). Retrieved November 11, 2010, from http://www.converters.tv/
Digital to Analog Decoder, Converts digital Audio to analog audio, Gefen TV GTV-DD-2AA. (n.d.). Retrieved November 4, 2010, from http://www.ramelectronics.net/audio-video/audio-converters-extenders/analog-to-digital-digital-to-analog/digital-to-analog-decoder-gtv-dd-2-aa/prodGTVDD2AA.html
GefenTV+Digital+Audio++to+Analog+Adapter. (n.d.). . Retrieved November 4, 2010, from http://www.gefen.com/gefentv/gtvproduct.jsp?prod_id=5279

Related articles

• Perfect sounds: building the perfect hi-fi (telegraph.co.uk)
• Yamaha Goes Classic: Hi-Fi Components Combine Rock-Solid Vintage Design, Modern Sonic Purity (prweb.com)
• Denon Celebrates Its 100th Anniversary With Debut of Special Edition Product Collection (eon.businesswire.com)
• Flat-screen TV upgrade 2010: What a difference five years makes (news.cnet.com)
• How to have the music quality of 30 yrs ago with today's music services (english.martinvarsavsky.net)

Vintage sound amplification - Leak TL/10 amplifier and Varislope II Pre-Amp

Having made my first sale on New Zealand's internet trading system, TradeMe, my appetite is whet for further sales.

I sold a motor caravan in behalf of my father, and now I am preparing to sell what I thought was a derelict valve (tube) amplifier.

As I Googled away my singing practice time last Saturday, what follows is a brief summary of the remarkable story of the Leak TL/12 series of ground-breaking hi-fidelity valve amplifiers that I discovered....

Here is the basis for my first draft of an advertisement for TradeMe. Most of the content is drawn from the references presented at the end of the posting.


Vintage Audio - Leak "Point One" TL/10 Power Amplifier with matching Leak Varislope II Pre-Amplifier
According to Classique Sounds (Leicester UK) Leak equipment is on the "most wanted" list for vintage audiophiles. This Leak TL/10 valve amplifier and Varislope II pre-amp was produced in the early 1950s by H. J. Leak & Co. Ltd, Brunel Road, London. This type of equipment is appreciating in value as vintage collectibles

Condition
The equipment in this auction was purchased by my father second-hand circa 1962 in Wales, then brought to New Zealand where it was used until the early 1980s. Since then, the equipment has been stored inside in dry but dusty conditions and has probably not been used for 25+ years. Accordingly, relevant precautions must be taken before powering it up and leaving unattended. The gold "orange peel" enamel is slightly blemished in several areas (See photographs). There has been no attempt at modification or restoration since its purchase in 1962.

I have carefully removed the dust from the equipment and powered it up. The power amp is activated and all valves glow in both the pre-amp and power amp. The loudspeaker to which I connected the equipment very quietly hums at 50 Hz. Input signals applied to the several inputs (tape input, phono, aux) produce no result in either the loudspeaker, or the pre-amp tape output.

Sound quality
According to one seller on TradeMe: "Connected to good front end sources and efficient speakers these amps are still impressive sounding, and are appreciating in value as vintage collectibles." (8)

Specifications: "Point One" TL/10 Power Amplifier
10 Watts output.
Low total harmonic distortion: <= 0.1 per cent at rated output. Valves: EF86, 6SN7, 2 x KT61 in ultra-linear. Leak pamphlet states that the Brimar 6AG6G is an exact equivalent to the KT61. 5Z4 rectifier. Gold enamel finish. Mono only. Original UK purchase price (catologue new): "Point One" TL/10 power amplifier (17 guineas). (9) AT least four weeks wages of the time! Specifications: Leak "Varislope II"
First released: August 1954
This pre-amp features higher input sensitivities than previous Leak pre-amps, and has improved appearance.
Two EF86 valves are used, with a similar shunt feedback circuits as used in previous pre-amps.
The disc equalisations provided are: BRIT-78, BRIT-LP, COL-LP, RCA-Ortho, AES and NARTB.
Tuner, Tape, Mic and Auxilliary inputs are also provided.
Tape output.
Bass and treble are switch boost and cut, with the variable slope facility available for treble-cut.
Steel front panel finished in gold enamel.
Mono only.
Original UK purchase price (catologue new):16 pounds 16 shillings (16 Guineas)

Circuit topology
All Leak power amplifiers (Except Type 15) use the same basic circuit topology as the TL/12 The Topology comprises a first stage of voltage gain (with either triode or pentode), a triode long-tailed pair phase-splitter/driver stage, followed by an output stage (triode, tetrode, or ultra-linear) with cathode bias using separate cathode resistors" A discussion of the valves used in the TL/10, and substitutes is presented in (4, 10).

History
In 1949, Harold Leak demonstrated the foundation of the product line, the TL/12 "to amazed Americans" at the Audio Engineering Society exhibition that was held in New York. (9) The TL/10 was introduced as a lower cost alternative to the famous TL/12, but maintained the distortion rating of 0.1%.

The Leak "Point One" range of amplifiers was named for the low distortion figures achieved: the then "astonishingly low total harmonic distortion - at just 0.1 per cent for 15 Watts output" (5) The age of High Fidelity (hi-fi) had arrived!

H. J. Leak & Co Ltd were "Designers and Manufacturers of Specialised Electronic Instruments for the Communications Industries". Harold Leak, founder of the company, was particularly concerned that his designs were built to exacting standards and a high quality of finish. Unusually for equipment aimed at the domestic market, Leak amplifiers were built with component boards and cable looms. There are no printed circuits, transistors, or integrated chips. Capacitors were soldered into position with the value and rating markings visible, and resistors all had their tolerance bands at the same end. (1)

The TL series was "very well constructed, and featured a power supply with no electrolytic capacitors. The oil-filled paper capacitors used instead were costly but have a much longer life. Wiring standards were impeccable, and all transformers were finished for tropical operation."

The TL/10 followed the introduction of the TL/12 in 1948. The TL/12 was designed for "quantity production" premised on sales to three classes of users: Professional audio engineers, the non-technical music-lover or gramophile, and the knowledgeable amateur enthusiast (the "audio hobbyist" of the U.S.) who had previously built his own amplifiers for reasons of economy and/or personal satisfaction. For instance, the BBC placed large orders for the TL/12 to use as a component of its patented Monitor Loudspeaker. (9) The "Point One" series may well be an first example of what we now term a "prosumer" product: a high-end consumer product that matches professional performance and manufacturing standards.

The TL/10 amplifier was the first Leak amplifier to "incorporate the "ultra-linear" output stage configuration (popularised by Hafler and Keroes from the USA in the early 1950's, but earlier proposed by Blumlein). Many consider the TL/10 to be much under-rated these days. Leak certainly did not skimp on the ratings or size of the transformers, as they are identical in size to the TL/12 Plus (and Stereo 20 in the case of the output transformer)." (10)

In late 1951 H. J. Leak & Company published "a 28-page treatise explaining the history, concept, and design of the TL/12 amplifier and the associated RC/PA/U pre-amplifier. This pamphlet makes for fascinating reading for anyone interested in the history of the valve amplifier development during the "golden age" of audio (from the late 1940's to the early 1960's)." (10)

Recent auctions
Leak TL 12 "Mono" Power Amplifier complete with RC/PA pre amp - UK Ebay £UK 1000 as at 2 days before close (2)

Leak Stereo 20 Valve Amp for sale - TradeMe.co.nz - New Zealand Last bid: $900 (8). No pre-amp.

TL/10 Pair, £UK 450, UK, Jan 1999 (11)

TL/10 - one only, NEW in box. Bidding to US$530, but the reserve was not met.

TL/10 - one only, with Point One mono pre-amp. VGC. CA, USA, US$266, March1999.

2 x Varislope III pre-amps, filter knob missing, others knobs un-original, New York, USA, US$133 pair

Point One Stereo Pre amp - with Gold Anodised Facia, Australian Auction,Aug 1998, A$140

Varislope 2 Stereo Pre-amp, Grey/silver, lettering worn, knob center missing,Canada, US$46.50, Jan 1999

According to Classique Sounds (Leicester UK) Leak equipment is on the "most wanted" list for vintage audiophiles:

• Leak Stereo 20
• Leak TL10
• Leak TL12/TL12+
• Leak TL25
• Leak TL50
• Leak Stereo50/60 etc

"Current value of a single TL/12 in fine fettle is anywhere between £500 - £1,000; although recently (August 2006) I saw a matched pair with early serial numbers and minor modifications (RCA input and input level control) reach £2400 (US$4,500) on eBay. The immaculate unit with preamplifier (pictured at right) fetched £1480 in March 2006." (11)

Restoration
Purchasers of this equipment are advised to have the equipment tested for safety prior to use or leaving unattended. Advice on history and restoration of Leak equipment is provided on the unofficial Leak Web site. The site is designed to "help encourage the restoration and maintenance of this wondeful audio equipment". (5) The site discusses resistors, capacitors, iron-cored components, connectors, and valves/tubes. Circuit diagrams are provided. (5)

Typical restorations include: "all capacitors and resistors replaced with good quality components, including film and foil coupling capacitors and the large dual section power filter capacitors. Replace input sockets and speaker terminals with better modern types." (8)

Service, user manuals and schematics, are also available from The Audio Circuit (TAC). (6)

An excellent series of photos illustrate and comment on the process of restoring a Leak Varislope. For instance, note the passion and perfection this restorer demonstrates: "Underneath as received. You don’t need to be an expert to spot that about a dozen components had already been changed here. Now, whilst there is no rule that says you can’t use radial and PCB mount components on a repair like this, I personally don’t think they look right. I decided to rip everything out and test/replace with the correct axial components." (7)

Restoration specialists
There are specialist restorers who rebuild Leak equipment. For instance, the restoration cost for a Leak Stereo 20 starts from £UK 199.00. I would expect the Point One restoration to be somewhat less expensive, since it is a mono rather than stereo device. (3) Of course, you may choose to acquire two Leak amplifiers so that you can create a stereo system.

There seem to be various alternative valves (tubes) that can be used to improve quality of performance. For instance: One restorer noted that: "All valves are good quality types, and are well matched and test to new spec or better. The input and phase splitter valves are Telefunken ECC83s; the output valves are Dutch made Philips ECC84s, and the rectifier is a Philips GZ34." (8). The unofficial Leak Web site also remarks on valve substitutions.

I have been advised of a local restoration specialist near my location in New Lynne. Accordingly, my next project is to get an estimate of the cost of restoration and/or just getting the fixed running in its "as is/where is" condition.

I make NO guarantees that this equipment will work. Furthermore, I make no guarantees that you will be able to locate replacement components. I have been advised that valves (tubes) are manufactured in Russia.



References
1. Leak TL/25 Plus audio amplifier and Varislope mono pre-amplifier - Object Wiki. (n.d.). . Retrieved April 18, 2009, from http://objectwiki.sciencemuseum.org.uk/wiki/Leak_TL/25_Plus_audio_amplifier_and_Varislope_mono_pre-amplifier.

2. Leak TL12 Point One Valve Power Amplifier + Preamp RCPA on eBay, also Separates, Audio, Vintage Electronics, Consumer Electronics (end time 20-Apr-09 10:39:50 BST). (n.d.). . Retrieved April 18, 2009, from http://cgi.ebay.co.uk/Leak-TL12-Point-One-Valve-Power-Amplifier-Preamp-RCPA_W0QQitemZ200330161874QQcategoryZ43804QQcmdZViewItem.

3. Classique Sounds (Leicester UK). (n.d.). . Retrieved April 18, 2009, from http://www.classiquesounds.co.uk/leak.htm.

4. Informazioni. (n.d.). . Retrieved April 18, 2009, from http://www.argaudio.it/index_file/Page492.htm.

5. H.J.Leak and Co. Ltd. - enthusiasts page. (n.d.). . Retrieved April 18, 2009, from http://44bx.com/leak/index.html.

6. Leak, Varislope 2 Stereo - manuals. (n.d.). . Retrieved April 18, 2009, from http://www.audiocircuit.com/index.php?c=LEA&m=Varislope%202%20Stereo.

7. Servicing of a Leak Varislope Stereo Hi-Fi Amplifier. (n.d.). . Retrieved April 18, 2009, from http://www.chambonino.com/work/hifi/hifi5.html.

8. Leak Stereo 20 Valve Amp for sale - TradeMe.co.nz - New Zealand. (n.d.). . Retrieved April 18, 2009, from http://www.trademe.co.nz/Electronics-photography/Home-audio/Vintage/auction-213553715.htm.

9. Leak TL/12 50'th Anniversary. (n.d.). . Retrieved April 18, 2009, from http://44bx.com/leak/TL12_50yrs.html.

10. Leak TL/10. (n.d.). . Retrieved April 18, 2009, from http://44bx.com/leak/TL10.html.

11. Leak TL/25 Plus - spot prices. (n.d.). . Retrieved April 18, 2009, from http://44bx.com/leak/prices.html.