[Won't Fix] Preview doesn't start at specified time

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tlhackque
Posts: 8
Joined: Sun Dec 20, 2015 1:06 pm

[Won't Fix] Preview doesn't start at specified time

Post by tlhackque » Mon Dec 21, 2015 11:10 am

Please describe the problem in as much detail as possible:
As noted in the feature request viewtopic.php?f=26&t=33725&p=157760#p157702,
preview seems to start at the beginning of the source (regardless of start time) and ends the specified length thereafter.

This is counter-intuitive; I expect the preview to begin at the start of the selected segment. That is, where the output file will start.

Here are the bug details.

What are the steps to reproduce this problem:
  • Normal profile
  • Open a DVD source
  • Select a title
  • Change "Chapters" to "Seconds" (Note this would be better labeled "time", as the time is in hh:mm:ss)
  • Select a start point - say 1/2 the length of the title
  • Specify an output file name
  • Click "Preview", leave default "start at" and "Duration", click Play.
  • Observe that the preview starts with second 0, not the selected start point
  • Click "Start"
  • Observe that the full conversion starts at the selected point


What version of HandBrake you are running:

0.10.2.7286 64-bit

What operating system and version and you running (e.g. OSX 10.11, Windows 7, Ubuntu 14):

Windows 7 Ultimate

If there was any exception or error displayed, please copy it and paste it here:

None

Please include the scan or encode log:

In this example, I opened a DVD with two titles; selected the first (00:58L35 length), selected a "seconds" start time of 00:27:00.

The logs were captured after the Preview step.

Scan log:
http://pastebin.com/eN4ridrS


Encode log:

Code: Select all

HandBrake 0.10.2.7286 - 64bit Version
OS: Microsoft Windows NT 6.1.7601 Service Pack 1 - 64bit
CPU: Intel(R) Core(TM) i7 CPU         950  @ 3.07GHz
Ram: 8183 MB, 
GPU Information:
  ATI Radeon HD 4800 Series - 8.970.100.1100
Screen: 1680x1050
Temp Dir: C:\Users\timothe\AppData\Local\Temp\
Install Dir: C:\Program Files\Handbrake
Data Dir: C:\Users\timothe\AppData\Roaming\HandBrake\HandBrake\0.10.2.7286

-------------------------------------------
No log data available... Log data will show when you start an encode. 

Open the log file directory to get previous log files.

User avatar
s55
HandBrake Team
Posts: 9545
Joined: Sun Dec 24, 2006 1:05 pm

Re: Preview doesn't start at specified time

Post by s55 » Tue Dec 22, 2015 8:26 pm

Previews start on preview boundaries (defaulting to 10), not the selected range. This is by design.
You can increase the number of previews per title/file in preferences but obviously this will have a fairly significant increase in scan time. It's not practical to go off and re-generate these every time the range changes.

Marking as Won't Fix.

tlhackque
Posts: 8
Joined: Sun Dec 20, 2015 1:06 pm

Re: [Won't Fix] Preview doesn't start at specified time

Post by tlhackque » Tue Dec 22, 2015 9:09 pm

I don't understand the rationale for this design decision. Or maybe I don't understand what HandBrake means by "preview". I'm a new user, so I may be confused.

I don't mean anything as dynamic as you indicate.

I am referring to the button on the GUI with the TV icon that seems to generate a single "preview" file from the input. I don't see that anything needs to be re-generated until that button is clicked.

I'm creating an output file. The output file will contain the selected range, which is the interesting part of the input.

I might want a preview of the output for two reasons. First, so see what the output will be (especially exactly where it starts) without doing the whole conversion. Second, to store a small download so a customer can decide if they want to download the entire output file.

If the preview started with the selection, the current behavior could be obtained by starting the selection at the beginning.

Why would I want a preview of material that won't be in the output? If "preview" means extracting some objects from the input that are identified as a "previews", your decision makes sense. In that case, I guess I'm looking for a different feature... and a better understanding of what exists.

Sorry if I'm being opaque.

mduell
Veteran User
Posts: 6681
Joined: Sat Apr 21, 2007 8:54 pm

Re: [Won't Fix] Preview doesn't start at specified time

Post by mduell » Wed Dec 23, 2015 2:26 am

Neither of those are what previews are for, so they don't behave how you want.

If you want small encodes from a particular point in the source... make that your encode.

kpflugshaupt
Posts: 63
Joined: Sat Feb 06, 2010 8:00 pm

Re: [Won't Fix] Preview doesn't start at specified time

Post by kpflugshaupt » Wed Dec 23, 2015 11:15 am

tlhackque wrote:I don't understand the rationale for this design decision. Or maybe I don't understand what HandBrake means by "preview". I'm a new user, so I may be confused.
I always took the preview as a means to judge output quality given the current quality settings.
E.g. how much quality do I gain when dropping a few points from the CQ slider? What difference does decomb make for this source? And so on.

The default behavior of converting 10 images from the source at equally distributed points serves this well, as you can quickly check different points of the source.

That's the usage Handbrake's "preview" appears to cater to. Your use cases (see the exact start/end of the output, produce a distributable preview) are not well covered by it.

Possible workarounds: For checking start/end times, do short test encodes at low quality. (This will be even faster than having Handbrake do start/end previews at full quality). For a distributable preview, queue up a second, time-restricted encoding run once you've found your setup.

Hope that helps
Kaspar

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