Anybody else in UK notice that Ch4 seems to have changed its transmission protocols on films such that the AC3 filter no longer works. It seems to be on recent films - there are some where it still works fine. Is it possible that TSDoctor is not detecting a more recent version of AC3? I have used 'Media Info' on the recordings and it doesn't detect any difference in AC3 between a recording that works and one that doesn't.
Could you offer a short sample of such a not working recording?
AC3 is a standard for more than 20 years. No changes known.
Or are you talking about EAC3 = DD+?
TS-Doctor should show you if it's EAC3 or AC3.
This one doesn't work: I have saved a few seconds that covers the movie start out of the break. It is 28MB so too large to post. I have attached the Media Info details on this clip.
cheers
My sample looks the same:
Audio #1
ID : 2306 (0x902)
Menu ID : 21200 (0x52D0)
Format : AC-3
Format/Info : Audio Coding 3
Format profile : Layer 2
Format settings, Endianness : Big
Codec ID : 6
Duration : 2 h 0 min
Bit rate mode : Constant
Bit rate : 384 kb/s
Maximum bit rate : 31.0 Mb/s
Channel(s) : 2 channels
Channel positions : Front: L R
Sampling rate : 48.0 kHz
Frame rate : 31.250 FPS (1536 SPF)
Bit depth : 16 bits
Compression mode : Lossy
Delay relative to video : -766 ms
Stream size : 330 MiB (4%)
Language : English
Service kind : Complete Main
Do you use Windows Mediaplayer for playback?
Did you try to use other mediaplayers for playback?
Just to be clear - the only thing that is not working is the AC3 filter for finding the Ad breaks. The film edits perfectly and plays back perfectly. Another Ch4 film recorded the same weekend works perfectly for the AC3 filter but looks the same in Media Info.
Prior to recent updates, Ch4 movies worked fine for the AC3 filter about 95%. Usually it was old movies (presumably without AC3) that didn't work. Recently it is perhaps 80% that don't work with the filter, and they are recent movies supposedly with AC3. Clearly something has changed!
It is not a big deal - I am just interested in why this should be!
I guess, what you see is just "normal" ;D
The AC3 filter works by assuming that film has 5.1 audio, whereas the ads are 2.0 only. Therefore the filter just looks for the change in the amount of audio channels.
If you start it on an old movie which does not have 5.1 audio, it cannot tell the movie from the ads, so it looks like it did nothing.
But its totally normal that the filter cannot work under these conditions. Nothing to worry about.
Normally the TSDoc already notices on the entry scan that there are no changes and so it skips the detailed AC3 scan later on.
But of course, if you have a recording containing several movies, the filter might be fooled by the changes and manages to isolate all (newer) movies whilst skipping over older ones.
Note that there are even some stations which ALWAYS send out 5.1 audio by upscaling the given channels artificially or just transmitting silence in the additional channels. Of course the AC3 filter cannot help you here too.
Thats why the doc contains serveral methods for ad scanning. Usually one of them will be "good" for your recording situation, it might not always be the same. So experiment a bit with them and try to find one which works better with your input material.
OK, a missunderstanding. You mean the AC3 commercial break detection, not the playback.
Mam is right. It works great for movies with AC3 5.1 but not good for older Movies with AC3 2.0.
So we may be back where I started surmising that Ch4 has changed its protocols. What is certain is that I have had films with AC3 5.1 where the AC3 filter didn't work. I mean that it simply wasn't available in the GUI, and if you forced it on then the ribbon turned red and (of course) it found no breaks. I have erased all the raw recordings but I'll do a bunch this weekend and get back.
Does the AC3 filter need to detect BOTH 5.1 & 2.0 content for it to become available in the GUI?
It is sort of ironic that we got the improvement in the Video Analysis mode (which now works fine on Ch4) so at least I have a back-up. I always edit manually (for accuracy) so the auto detect is just a start point.
To repeat - I am a happy camper but curious as to unexplained changes.
Zitat von: PerryM am November 29, 2017, 12:57:56
Does the AC3 filter need to detect BOTH 5.1 & 2.0 content for it to become available in the GUI?
Because it triggers on the edge of a change:
OF COURSE! ;D
In the settings you can select how many samples the quick scan will do (default 18 or so). Within these samples there needs to be at least one change, else the filter will be skipped during further analysis. If you think it misses too often (you KNOW that there are changes, but they are not discovered automatically), raise this number. But beware that more samples also will mean a longer time for the quick scan to run.
There is another option: "prefer 5.1 channels". If selected the Doc thinks that 5.1 audio parts are part of the movie, otherwise it treats them as ads and selects the parts with 2.0 audio instead. Usually you dont need to bother with this one.
We are again rather missing my point.
When you first load a TS file in the GUI, it reads the metadata and immediately offers to detect the commercials with 'Video Analysis' or (sometimes) AC3 mode. What allows the AC3 mode to be presented? It is clearly NOT the presence of an AC3 5.1 audio track (at least, in the present version of TSDoctor).
I shall check all the settings tonight (I am at work) to see if any have changed.
Zitat von: PerryM am November 29, 2017, 19:04:53
What allows the AC3 mode to be presented?
As far as I know it MUST be the detection of a channel change in the AC3 audio track. The whole filter makes no sense without an AC3 track.
I cant get Ch4 here (or? hmm, maybe I can, have to check. But then, it would only be a valid check if I could get it from the same source as you do. Different Sats may transmit different tracks, even for the same station) therefor I cant take a look.
but maybe Cypheros knows about another reason why this filter may be selected? ("use the source Luke....!")
Lately I had a similar effect on a recording from a german TV Station. TSD read the file and immediately started EPG Recognition - obviously because it found no AC3 Changes respectively commercial breaks.
Since I was sure there must have been commercials I manually started AC3 recognition and tadah: 4 Changes.
Zitat von: wolfman am November 30, 2017, 08:51:31
TSD read the file and immediately started EPG Recognition - obviously because it found no AC3 Changes respectively commercial breaks.
Wrong too ???
This behaviour is also "normal". It comes from the precedence of the filters during quick scan. Like in the old Video game "Joust" ("...the higher lance wins!") is the test sequence (which is hardcoded into the doc) important. Once a filter reports that it found the needed infos in the recordings, lower filter tests are completly skipped.
So it never got to the point where it might have discovered the AC3 stuff.
The EPG scan comes ahead of the AC3 scan, therefor your file has never been tested at all against audio changes.
The main problem here is that the sequence of tests is hardcoded. Its not transparent to the user why sometimes this filter is picked and sometimes a different one.
Users assume that it would be always "the best", but thats far from reality. If you wanted this, it would be needed that ALL filters would have to be run in full lenght and then the final results (who found more blocks?) would have been compared, finally chosing the one that produced the most detailed results. But that would take ages, so the doc does only quick scans and picks the one that first reports it might produce a result.
You will ever have situations where you need to choose manually and then run your desired scan by hand afterwards.
Thank you, didn't know this
Or in German "wieder was gelernt"
In the log you can find a sequence of audio information:
Audio stream 1: MPEG1/Layer2 2.0 48000Hz (NAR)
AC3 2 channels: 18 times
Audio stream 2: AC3 2.0 48000Hz (ENG)
EIT data found
So TS-Doctor checked at 18 different positions of the recording for the number of channels. In this sample it's always "AC3 2 channels". No AC3 commercial scan is offered because it's unlikely that commercials can be detected with this methode.
Here is another sample but this time different numbers of channels are detected. This time TS-Doctor will offer and prever AC3 commercial detection because it's very likely, that commercials can be detected with this methode:
Audio stream 1: MPEG1/Layer2 2.0 48000Hz (DEU)
AC3 2 channels: 6 times
AC3 6 channels: 12 times
AC3 detection mode: Prefer 5.1
$0203 2 different AC3 types detected!
$0203 selecting AC3 type with mode 5.1
Audio stream 2: AC3 5.1 48000Hz (DEU)
So (for the sake of experiment) I recorded 6 Ch4 films this weekend. The result was that ALL worked on the AC3 filter! (all had 5.1 audio track)
I wanted to say that something must have changed on Ch4 transmissions, but for the sake of completeness I have to report that Windows 10 had a major update during this week.
As I mentioned, I no longer have the raw files that didn't work so it may have to remain a mystery!
Reading Cypheros explanation does now spur one possible explanation:
A few weeks ago when I noticed the 'problem' - Ch4 was very short of commercials late at night when most films are transmitted, so the commercial breaks were very short. It is thus quite possible that a few random samples didn't happen to hit a single one. They now have lots of Christmas commercials so the breaks are much longer.
Just a thought.
Zitat von: PerryM am Dezember 04, 2017, 11:29:19
It is thus quite possible that a few random samples didn't happen to hit a single one. They now have lots of Christmas commercials so the breaks are much longer.
Just a thought.
If you think this might be the problem, you can enlarge the numbers of samples taken in the options. This will slightly encrease scan time of course, but may also produce better results in detecting smaller breaks.
If you still kept a problematic recording, you can play a bit with it and keep doubling the value until you are pleased with the outcome. If the scantime becomes too long, you can still decide which value to use.
There will be always a tradeoff somewhere :'(
@Cypheros:
Maybe you should add a new list to the doc. Users could select their prefered scantype for a certain channel. If there is an entry in the list, the autocheck is skipped, instead the user's filter is instantly run on loading a new file. I also have that "problem" on Servus TV HD, the autocheck always select the EPG Filter, but its useless, you need to run VA on this channel for better results. So a "manual overwrite" would be a nice thing to have...
Zitat von: Mam am Dezember 04, 2017, 18:05:37
Maybe you should add a new list to the doc. Users could select their prefered scantype for a certain channel. If there is an entry in the list, the autocheck is skipped, instead the user's filter is instantly run on loading a new file. I also have that "problem" on Servus TV HD, the autocheck always select the EPG Filter, but its useless, you need to run VA on this channel for better results. So a "manual overwrite" would be a nice thing to have...
I'll second that. :)
Version 2.1 will have that.
Zitat von: Cypheros am Dezember 05, 2017, 01:49:16
Version 2.1 will have that.
:-*
And when are we supposed to have 2.1 ? ;D
Yes somewhere in the future :)