Virtualdub or Avidemux better to cut FLVs with no quality loss?

[gumbygum]

I want to cut out parts of FLV videos and save the edited movie with the same quality as the original. I understand that Virtualdub can apparently do this with Direct Stream copy if you use the FLV input plugin. Then you can save the FLV as AVI with, I think, no loss in quality (correct me if I'm wrong).

However, I also understand that Avidemux can edit FLVs. But I don't know if its Direct Copy function works with the FLV format. I haven't found the answer to that on the net.

Can you give me your opinions on which program would be better or easier to edit FLVs with no quality loss?

Also...if i want to cut on a frame that's not an I-frame, will both programs do "smart rendering", i.e., re-encode only those frames around the cut, while directly copying the rest of the video? Again, I haven't found an unambiguous answer to this -- i have seen some opinions on this forum that smart rendering only works with certain formats and not with FLVs. Does anyone know the answer?

Thanks for your help.

[poisondeathray]

virtualdub cannot use direct stream copy with flv, only with avi

smart rendering only works with xvid/divx

flv's can hold different types of audio/video. It is a container format. Not all formats are supported directly by either program. Use mediainfo (view=>text) to find out more information

[gumbygum]

[quote="poisondeathray"]virtualdub cannot use direct stream copy with flv, only with avi /quote]

I don't think this is correct. I followed Moitah.net's advice re their FLV input plugin:

"To convert FLV to AVI without any editing or filtering, load a FLV in VirtualDub, make sure "Direct Stream Copy" is selected in both the Video and Audio menus, and choose "Save as AVI" from the File menu."

Apparently this worked. I didn't make any cuts, I was just testing the plugin. It saved the file as AVI very quickly so I don't think it re-encoded. The test file seems to have the same quality to my naked eye as the original.

[poisondeathray]

What kind of flv? I don't think direct stream copy in vdub would work for h.264/aac from youtube for example, but this format would work in avidemux (because aac is incompatible in avi container, but fine in flv or .mp4, both of which avidemux supports)

[Gavino]

The FLV plugin for VDub doesn't recognise h.264/aac FLV's anyway. You have to use the DirectShow input plugin for that, and it doesn't support Direct Stream Copy. Nice to know that the FLV plugin does though.

BTW Avidemux doesn't recognise h.264/aac FLV's either, only in mp4.

[poisondeathray]

BTW Avidemux doesn't recognise h.264/aac FLV's either, only in mp4.

Good point, I guess you could use flvextract and yamb to re-wrap then avidemux

But there is no logical reason why avidemux shouldn't work with h.264/aac these days, it just has to be updated with new flv splitter

[hech54]

I've never had any luck opening FLVs in anything but a player....

[Gavino]

Good point, I guess you could use flvextract and yamb to re-wrap then avidemux

Yes, that's exactly what I do.

But there is no logical reason why avidemux shouldn't work with h.264/aac these days, it just has to be updated with new flv splitter

That's right, but the latest version I tried recently (2.5.1) still hadn't been updated.

[gumbygum]

What kind of flv? I don't think direct stream copy in vdub would work for h.264/aac from youtube for example, but this format would work in avidemux (because aac is incompatible in avi container, but fine in flv or .mp4, both of which avidemux supports)

According to mediainfo, the video is VP6

[gumbygum]

This is all a bit confusing to me. Well, if i have a h.264 FLV that I want to edit without losing any quality, what do I do? Can I use FLV Extract to convert it to an avi, and then edit it in Virtualdub or Avidemux? Will FLV Extract convert an h.264 without quality loss?

But if the FLV is an h.264/aac, it cannot be extracted to make an AVI because it's incompatible with AVI? So FLV Extract won't work?

but I thought I read that FLV Extract is also incompatible with h.264/aac.

So...as long as my FLVs are not h.264s, I guess there's no problem cutting them and saving without re-encoding in Virtualdub?

Also no problem in Avidemux? But which program is better for this task?

So neither Virtualdub nor Avidemux can edit a h.264/aac without re-encoding?

[poisondeathray]

New versions of flv extract work fine with h.264/aac in flv

For h.264/aac in flv, use flvextract to demux, yamb to re-wrap in .mp4, then avidemux to cut, leave container as .mp4. The problem is aac audio which isn't supported in avi container. Vdub can only export avi.

[Ai Haibara]

Actually, according to the AVI-Mux GUI myths page, under the heading "AAC in AVI does not work", AAC audio is supported in the AVI container.

Whether or not you really should put AAC audio in an AVI... now, no comment.

Edit: originally had the words 'myths page' be the link to the page, but with VH's auto-linking for 'AVI-Mux GUI,' I thought it might get a little confusing.

[gumbygum]

New versions of flv extract work fine with h.264/aac in flv

For h.264/aac in flv, use flvextract to demux, yamb to re-wrap in .mp4, then avidemux to cut, leave container as .mp4. The problem is aac audio which isn't supported in avi container. Vdub can only export avi.

Thanks for that suggestion. After you use yamb to re-wrap in mp4, why should you use Avidemux to cut and not Virtualdub?

So is there no way to cut a FLV on non-I frames with smart rendering in either Avidemux or Virtualdub? Even if you first convert it to an AVI or MP4?

So one is limited to cutting on I-frames if one wants to edit without re-encoding the whole movie?

[V1de0Luvr]

But there is no logical reason why avidemux shouldn't work with h.264/aac these days, it just has to be updated with new flv splitter

That's right, but the latest version I tried recently (2.5.1) still hadn't been updated.

The SVN (beta) builds of AviDemux 2.5.1 do work with FLV and MP4. One minor restriction is that an FLV must be saved as MP4 after editing in AviDemux. When H264 is detected, it warns about possible frame inaccuracy (or something), but I have not tried the latest build 5546 from Nov. 23rd, yet.

[lordsmurf]

I've not found any way to demux+remux or cut/splice FLV On2 VP6.

[poisondeathray]

I've not found any way to demux+remux or cut/splice FLV On2 VP6.

Are you saying avidemux doesn't work on those clips? They are a standard format. Is the audio mp3? Even vdub works on those if you have vp6vfw installed (but you are limited to exporting in AVI container), as should FLVExtract

[Gavino]

After you use yamb to re-wrap in mp4, why should you use Avidemux to cut and not Virtualdub?

You could use VirtualDub, but you would have to do it via the DirectShow input plugin (requiring re-encoding).
And in that case, you could just have done the same with the original flv file.

So is there no way to cut a FLV on non-I frames with smart rendering in either Avidemux or Virtualdub? Even if you first convert it to an AVI or MP4?
So one is limited to cutting on I-frames if one wants to edit without re-encoding the whole movie?

That's correct. As I understand it, Avidemux supports smart rendering only for ASP (xvid) in AVI.

[gumbygum]

Thanks for all your helpful info. I hope in future updates Virtualdub and Avidemux will fix all these limitations so we can edit h.264 and use smart rendering with many more formats.

What about non-freeware video editors? can any of them do all this stuff (direct copy, smart render) with all, or at least a lot more, of the various formats?