[Rejected] video passthrough

[ltwally]

I saw others talking about this in the Mac request forum. I think it should be a request for all versions of Handbrake:

VIDEO PASSTHROUGH

On occasion I find videos with perfectly acceptable video, but with high bitrate DTS or PCM audio that I wish to transcode to AC3 or AAC.

Best of all, for you developers, it should be very easy to implement.

Please add it to your to-do list.

Thanks.

[s55]

It's actually not easy to implement. HandBrakes engine is wasn't designed to support video passthru and adding it in after the fact is major work. There is a whole host of problems that would need to be solved, especially when it comes to A/V sync so it simply isn't practical to add this to HandBrake.

Don't get your hopes up.

[drfrogsplat]

I have found Subler (Mac only) to be a useful alternative for video passthrough with simple modifications to audio.
Also MP4Tools handles independent passthrough vs transcoding of video/audio/subtitle streams.

Some limitations on video codecs/containers... useful if you're aiming at H.264 (x264) in mp4/m4v container (and possibly mkv also).

[qpirsel]

That's really sad. I just logged in to request this feature also while I saw this post. My collection of HDTV (TS-Files) records is rising daily and it makes no sense to recode the h264 video source only to get them into a MP4 container (my favourite container format). Anyway I accept that handbrake wasn't designed for re-muxing and that it's nontrivial to implement this feature.

Regards
qpirsel

[ltwally]

I apologize for the incorrect assumption on the ease of implementing this concept. To my mind, it seems simple... but perhaps I was assuming that handbrake had more built into it than it does. I was thinking you already had code to read video frames/packets and another to write them. But if that is offloaded to some x264 code, I could see how it would dramatically increase the time to implement as well as the cost to maintain the feature.

That being said...

Anyone know of a good WINDOWS application that can be used for transcoding ONLY the audio ?? It kinda stinks having to find yet more tools just because some people feel the need to use 1.5 mbps DTS for simple video files when AC3/AAC at a forth of that bitrate would totally suffice.

[TedJ]

It kinda stinks having to find yet more tools just because some people feel the need to use 1.5 mbps DTS for simple video files when AC3/AAC at a forth of that bitrate would totally suffice.

Perhaps you just need to be more discerning about downloading your pirated rips.

[Deleted User 11865]

I apologize for the incorrect assumption on the ease of implementing this concept. To my mind, it seems simple... but perhaps I was assuming that handbrake had more built into it than it does. I was thinking you already had code to read video frames/packets and another to write them. But if that is offloaded to some x264 code, I could see how it would dramatically increase the time to implement as well as the cost to maintain the feature.

The problem is not passing the video through. HandBrake's entire A/V sync code is based on the assumption that we can drop, duplicate or change the duration of video frames. This is not possible if we're passing video through.

[ltwally]

It kinda stinks having to find yet more tools just because some people feel the need to use 1.5 mbps DTS for simple video files when AC3/AAC at a forth of that bitrate would totally suffice.

Perhaps you just need to be more discerning about downloading your pirated rips.

Ok.... I'm new here. But your reply reads like pure flamebait. I'll assume that, you being a moderator, are above that and that this is your idea of a serious reply.

Sometimes there are no alternatives. Or the alternatives which contain audio at sane bitrates have crappy video.

So, your reply did nothing to help me. Thank you for trying through. And I mean that with absolutely no sarcasm.

[TedJ]

No, that was me making a rather pointed reference to forum rule #3, which you agreed to abide by when joining this forum.

viewtopic.php?f=6&t=6702

[ltwally]

I said nothing about pirated material. You said that. I did not even imply it. If you wish to infer such, that is on you.

If you had actually though to ask, I could have told you that I am a big buff of concert bootlegs, which are completely legal (at least in the USA), so long as they are not sold at profit. I could have told you that bootleggers often feel the need to include the most ridiculously high bitrate audio sources, such as PCM and DTS, for recordings that weren't all that incredible to begin with.

But you didn't ask. You jumped to conclusions. And then made pointed references in a manner that some might have found inflammatory.

But not me. Because I know you were just trying to help.

[bluesdealer]

Yeah, it's really too bad that HandBrake can't do this. The video passthrough feature has become pretty standard, even among lesser converters. Needlessly converting H.264 in an inherently lossy manner, merely to change containers, is just wasteful and pointless when remuxing (and maybe adding an AAC stereo track) is all that is needed. I rarely use HB anymore because of this serious shortcoming, which is a shame because I used to love the app. Since most video out there is H.264 and in either MP4/M4V or MKV containers, there's just no point.

Here's to hoping the devs have a change of heart when it comes to adding this much-needed capability.

[TedJ]

Since most video out there is H.264 and in either MP4/M4V or MKV containers, there's just no point.

Care to elaborate?

As you've pointed out above, the answer is remuxing... something HandBrake has never claimed to be.

[bluesdealer]

Since most video out there is H.264 and in either MP4/M4V or MKV containers, there's just no point.

Care to elaborate?

Not sure what elaboration is needed. A few years back, Flash, WMV, and DivX were most common. Nowadays, content creators are opting for Flash or the more advanced H.264.

As you've pointed out above, the answer is remuxing... something HandBrake has never claimed to be.

I realize this. I was simply stating HandBrake would be a better program if it did support this functionality because it would yield higher quality conversions in less time. It already passes through audio when doing so makes the most sense for the desired output. A common example would be converting an MP4 or MKV file with H.264 video, but a nonstandard audio stream, for Apple TV. Many files just need a small bit of converting without changing everything.

[Deleted User 11865]

Our entire A/V sync pipeline is written with the assumption that we re-encode the video (so we can do anything with it, such as change the frame duration, drop or duplicate frames, etc.). This is not possible with video passthrough.

Feel free to re-write HandBrake in your free time.

[jamiemlaw]

This is why we have programs like Subler. If you have a Mac, you can use that. I wonder if it's possible to write a CLI wrapper for Subler so it can run under Windows.

[TedJ]

There are several mp4box GUIs that offer similar functionality, IIRC.

[bradycl]

eac3to, vob2mpg, there are a lot of tools, both cli and gui, to extract the audio stream. putting the new stream back in after you convert it should be easy with mkvmerge for mkv or mp4tools for mp4 if you're just looking to put in a basic ac3 stream after you've converted your audio. Take a look at the tools sections on the doom9 forum. There should be something there to cover (almost) anything you want to do.