Panasonic HDD recorder: Which recording mode for files to be used on PC?

[EasyLee]

I recently started downloading TV recordings from my Panasonic DMR-BCT730 Blu-ray recorder to my Windows PC using MediaMonkey, as described in this thread. Some users in that thread claim that there are compatibility issues with video players and converters with files recorded in DR mode. They recommend having the recorder convert DR recordings to one of the HD formats HG/HX/HE/HL/HM (in order of decreasing quality) before downloading the files to the PC.

Can anyone enlighten me about the difference between DR mode and HG mode (the highest quality conversion mode)? And can anyone confirm that DR recordings really cause trouble?

The Panasonic's user manual says basically that DR recordings are lossless and can contain several audio tracks while HG recordings are lossy and contain only one audio track. Why is it then that files converted to HG mode are about 10% larger than the original DR recordings? That doesn't make any sense. The only thing I can say is that there is no perceptible difference in quality between them.

What if I convert the recordings (.ts files) on the PC to .mp4 anyway, using something like Handbrake or Avidemux, getting rid of additional audio tracks? Does it still matter what the recording mode was? I noticed that neither of these two apps have any trouble opening DR recordings.

 

[LV426]

DR recordings are an exact copy of the broadcast transport stream, with no process applied in the recorder. They are thus identical to the received broadcast.

The original broadcast is compressed. Thus it will be somewhat degraded from whatever the original source was. But it is as good as you can get.

In order to play back directly (or to re-encode) - the player first has to decompress to create a sequence of separate images. In so doing it does not - can not - restore anything that was lost in the encode. Thus you start any such process with whatever shortcomings the original received broadcast contains.

EVERY (re-)encode is a degrading process. All encoders use some sort of compression to limit file size and compression is always degrading. Even if you re-encode to a larger size it's still a (re-)compression (with attendant degrade) of the previously compressed content.

In terms of PC playback, I have found that VLC behaves just fine with the .tts files of a DR recording. And again, so doing means you are playing back exactly what was transmitted; you can't better that.

If you want to import into some editing software then you may encounter compatibility issues there. There are ways around that that don't involve re-encoding beforehand (although if you do edit, the end product will need re-encoding either in part or fully).

 

[Gavtech]

And can anyone confirm that DR recordings really cause trouble?

The 'trouble' you are referring to is probably that BR discs which have had titles transferred to them in DR mode can only play on machines that support DR mode, and not all do.

Thus it is recommended that if universal playability elswhere is required, that disks are burned in one of the other modes - which is much less efficient but does provide universal playability.

Since you are wishing to transfer titles to a PC, the problem does not apply.

 

[EasyLee]

So would you say the following approach to archiving recordings is sensible?

• Record in DR mode
• Download .ts file to PC
• Open .ts file in Avidemux, trim beginning and end, discard all but one audio track
• Save as .mp4, either without re-encoding or with re-encoding applied to further compress file size

The alternative would be to have the Panasonic re-encode the recording to something with a lower file size (e.g. HX or HE modes) and then use Avidemux solely to trim and repackage the video stream from the .ts container to the .mp4 container without re-encoding.

Obviously, you have more control over the re-encoding with something like Avidemux or Handbrake, because it allows you to precisely set the desired quality. But if the Panasonic's re-encoding algorithm was superior to Avidemux I would still have the recorder do it.

The 'trouble' you are referring to is probably that BR discs which have had titles transferred to them in DR mode can only play on machines that support DR mode, and not all do.

I can't play burned BR discs on my PC anyway, no matter if the video content on them was recorded in DR or any other mode. Someone told me this was because the BR discs created with the Panasonic are in the BDAV format, as opposed to BDMV which is the format of commercial discs.

 

[LV426]

If you only need very basic editing (trim top and tail, for example) then that should work, I think. The only bit I'm uncertain about is the .mp4 container. But try it. And I'd suggest - only re-encode if you have to. Broadcast/recorded (DR) .tts files are generally quite small anyway and you will degrade further when you re-encode, regardless of the chosen quality. And it takes waaaayyy longer to process. Suggest you stick to the "copy" option in Avidemux for both audio and video.

 

[EasyLee]

Well, these files are not that small I think. In DR mode a 90 min film is about 6 GB. Handbrake or Avidemux can re-encode it to half the size with barely noticeable degradation.

For what it's worth, I've just done a little test to compare re-encoding in the Panasonic recorder to Handbrake/Avidemux. I recorded 10 mins in DR mode, then made a copy in HM mode (which is the lowest quality HD mode). Then I downloaded both to the PC. Next, I loaded the DR file into Handbrake and Avidemux and had them re-encode the file to .mp4 so that the resulting file size was identical to the HM recording (rate factor was 23).

The HM conversion off the Panasonic showed noticeably more artifacts than the conversions done with Handbrake and Avidemux - at the same file size. I concluded that conversion with these apps is more efficient than conversion in the Panasonic.