Film-Tech Forum ARCHIVE: Direct Play/PlayWhileIngest on Dolby Servers?

This is topic Direct Play/PlayWhileIngest on Dolby Servers? in forum Digital Cinema Forum at Film-Tech Forum ARCHIVE.

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Posted by Carsten Kurz (Member # 5396) on 10-20-2014, 12:19 PM:

Some servers offer an option to play content directly from the distribution drives (GDC), or from the network with some prebuffering (e.g. Doremis or Sonys PlayWhileIngest feature).

I heard that recent Dolby software supports something like that, can anyone confirm or give detail?

- Carsten

Posted by Brad Miller (Member # 2) on 10-20-2014, 01:05 PM:

It's very easy. When you click the "open" button to select a playlist or direct content, simply click on the removable drive option instead.

Posted by Jim Cassedy (Member # 4115) on 10-20-2014, 01:22 PM:

As far as I know all the Dolby software versions supported this.

I work in several screening rooms (one of them at actually AT Dolby labs!)
and I've done this on numerous occasions where the hard drives didn't
arrive till the last minute or were being brought "in person" by a client
so there's no time to ingest before a screening.

However, as far as I know, this can only be done through the CRU bay.

I know you definitely can't do it from a USB stick or a mini-drive
plugged into the USB port, and I'm not sure the data transfer rate on
the SATA interface port is fast enough to support 'live play'.

(I've never tried. I'll be at Dolby later today & mabye I can see if it works)

Posted by Carsten Kurz (Member # 5396) on 10-20-2014, 01:47 PM:

Yes, the limitations are a bit strange, but some may be historical. Doremis will only do it from network sources, that have been setup and qualified for live play in the ingest manager. The rational behind this was probably that no 'raw' distribution data should be played, but only content that had been pre-ingested and verified on another Doremi or TMS. Sony R320 will only PlayWhileIngest from network folders through FTP and obviously assume an LMS/TMS as the source. R510/515 do not yet support that feature. Dolby supporting it from CRU seems that they believe the necessary data rate can be supported by CRU/SATA (which is true). Both Doremi and Dolbys have only USB2.0 ports, so PlayWhileIngest is out of the question over these ports. Same for GDC.

Typical data rates for DCPs during live play is around 25-35MByte/s. Todays drives support this without a problem, if they are okay and do not suffer from drive degradation. But it's not possible over USB2.0.

There is always a risc to do this, since the content being read from the disc has not been pre-verified for integrity, and distribution drives can have all sorts of issues, bad sectors, etc. Still I think that most drives will probably perform okay, at least if a large buffer of a couple of minutes is used. I know a small theater playing their arthouse series (one screening per week) direct from distribution drives on their GDC. Seems that so far they are doing fine. The issue, however, is that especially art house features arrive on USB/notebook drives very often nowadays, and only the most recent servers support USB3.0.

- Carsten

Posted by Steve Guttag (Member # 268) on 10-20-2014, 04:29 PM:

Dolby has been able to do this from the get-go...they were really the first that could play right off the CRU.

Another thing you can do with Dolby is to start ingesting and then play off of the drive...by the time your show is over, it will also be loaded so you can play off the RAID for the next show.

How to play off the drive was detailed by Brad above.

Note, on a DSS220, you can hook an eSATA/SATA cable to a CRU dock and the eSATA port on the front or rear and also play off of the CRU drive.

Posted by Marcel Birgelen (Member # 6801) on 10-20-2014, 06:35 PM:

quote: Carsten Kurz
Typical data rates for DCPs during live play is around 25-35MByte/s. Todays drives support this without a problem, if they are okay and do not suffer from drive degradation.

Another thing that might hurt is drive fragmentation, at least I think that was the issue in this particular case. Although modern file systems will try to keep it to a minimum, stuff can get ugly at times. I've seen this once, where a bunch of "custom made" content needed to be played from the disk, but this disk had been extensively used for other purposes before. The disk failed to perform and you barely got 10MByte/s reads off of it via eSATA after I hooked it up to a Linux box for some post-mortem diagnostics. Smart was not showing any issues with the drive, but after a "reformat", everything was back to normal.

Posted by Carsten Kurz (Member # 5396) on 10-20-2014, 08:52 PM:

That is true, but distribution drives, if done properly, will usually not be used like this, but always be formatted before copying, or even with sector-copying applied. The largest amount of data on DCP drives are the MXF files, these are usually few, but very large files. So, with commercial DCP drives, fragmenting shouldn't occur.

However, unlike common interleaved video/audio files, DCPs need access to at least 2 separate files during playout - video and audio mxf. But again, todays drives with transfer rates of 100+ Mbytes/s and large caches will usually cope with that.

I brought up this thread specifically because festivals regularly have two technical issues - little time to prepare/ingest features, and not enough space on the server RAIDs to have all the festival content ingested at the same time.

Then again, a lot of festival content arrives on USB drives, but USB3.0 is used more and more. But with CRU or eSATA chances for PlayWhileIngest or DirectPlay would be better.

- Carsten

Posted by Mattias Mattsson (Member # 4308) on 10-21-2014, 01:57 AM:

A really nice feature of Doremis is that you can connect several USB-disks and queue up the ingests without manual intervention once it has started.

I used this at a festival (together with a USB-hub) to ingest about six features from individual (slow) USB-disks overnight.

As far as I know this is not possible on a Dolby without manual work.

Posted by Marco Giustini (Member # 4544) on 10-21-2014, 04:51 PM:

The CRU is basically a SATA connection, that's why you can only play from a CRU or a SATA disk.

It also works on a DSP100.