Steam Copy vs. Direct Stream Copy

[Sound Master]

In VirtualDub2, there's Steam Copy and Direct Stream Copy. What's the difference between them? Are they both lossless?

Also, for the latter I can't change priority back to internal AVI driver or switch the default driver to it. How do I fix that? My videos are AVC/HEVC in mp4/mkv/mov files.

[dellsam34]

Depends on what format you are processing to, If outputing as HuFFYUV for instance, the processing will be lossless compression, if a lossy format is chosen then the output will be lossy.

[Sound Master]

Depends on what format you are processing to, If outputing as HuFFYUV for instance, the processing will be lossless compression, if a lossy format is chosen then the output will be lossy.

For Stream Copy?

By the way, can you answer this?
https://forum.videohelp.com/threads/413904-Different-Sounding-Audio

[dellsam34]

For full processing.
I don't know what you are asking for in those audio clips, what is it that you are looking for? and why does it matter if they are different?

[Sound Master]

For full processing.
I don't know what you are asking for in those audio clips, what is it that you are looking for? and why does it matter if they are different?

I want to know why they sound different. And what about my other questions about stream copy and direct stream copy?

[Alwyn]

In VirtualDub2, there's Steam Copy and Direct Stream Copy. What's the difference between them? Are they both lossless?

I have VDub2 and mine doesn't have "Steam" (or Stream) Copy. It only has Direct Stream Copy. Direct Stream Copy is lossless.

[Cornucopia]

For full processing.
I don't know what you are asking for in those audio clips, what is it that you are looking for? and why does it matter if they are different?

I want to know why they sound different. And what about my other questions about stream copy and direct stream copy?

From what I can tell, they all sound similarly average/mediocre.


Scott

[Sound Master]

In VirtualDub2, there's Steam Copy and Direct Stream Copy. What's the difference between them? Are they both lossless?

I have VDub2 and mine doesn't have "Steam" (or Stream) Copy. It only has Direct Stream Copy. Direct Stream Copy is lossless.

https://sourceforge.net/p/vdfiltermod/wiki/direct_copy/

[Attachment 78158 - Click to enlarge]

[Alwyn]

I beg your pardon, you're right; I don't use that menu much. I suspect that "Stream Copy" is not lossless if you're "copying" a lossy format (as Dellsam alluded-to in the second post). As you've probably found, you cannot do a Direct Stream Copy on a MP4-type file, only a lossless AVI eg LAGS, HUFF.

I did a quick test on an MP4; using "Stream Copy", the video bitrate was around 700kb/sec whereas the original file was 500kb/sec, so I think it is fair to say that that is not a lossless copy.

[Sound Master]

I beg your pardon, you're right; I don't use that menu much. I suspect that "Stream Copy" is not lossless if you're "copying" a lossy format (as Dellsam alluded-to in the second post). As you've probably found, you cannot do a Direct Stream Copy on a MP4-type file, only a lossless AVI eg LAGS, HUFF.

I did a quick test on an MP4; using "Stream Copy", the video bitrate was around 700kb/sec whereas the original file was 500kb/sec, so I think it is fair to say that that is not a lossless copy.

How do I find the video bitrate?

[jagabo]

Both Export -> Stream Copy and Video->Direct Stream Copy are lossless. You can easily verify this by comparing the two output videos.

[Alwyn]

How do I find the video bitrate?

Open the file in Mediainfo. Choose the "Text" view.

@Jagabo, I'm getting different video bitrates on an MP4 with Stream Copy. How can that be lossless? I can't Direct Stream Copy an MP4.

[jagabo]

MediaInfo isn't reliable as far as bitrates are concerned. Sometimes it reports the bitrate flagged by the container metadata. Sometimes it computes it via other parameters.

A simple AviSynth will show you the are the same:

v1 = LWLibavVideoSource("video.mkv") 
v2 = LWLibavVideoSource("video.mp4") 

Subtract(v1, v2).Levels(120,1,136,0,255)

Any differences will be very obvious.

[Alwyn]

This Stream Copy "lossless" copying appears to be not frame-accurate. I selected 253 frames for export and got 263 frames. I assume it's cutting only on the I Frames.

[Sound Master]

This Stream Copy "lossless" copying appears to be not frame-accurate. I selected 253 frames for export and got 263 frames. I assume it's cutting only on the I Frames.

It adds extra frames when cutting at I-frames. But when I'm not, Stream Copy is not frame accurate.

[jagabo]

This Stream Copy "lossless" copying appears to be not frame-accurate. I selected 253 frames for export and got 263 frames. I assume it's cutting only on the I Frames.

Of course. Every "lossless" cutter can only cut at i-frames.