What happens to the empty NAV packets in this case?

[dlflannery]

I author DVD's from TiVo Medium Quality files which are 352x480, half-D1 mpeg2. Following a popular fashion I output them from VideoReDo as .vob, rename to .mpg and input them into DVDStyler (which uses DVDAuthor). I understand the .vob from VRD has empty NAV packets that are needed by DVDAuthor.

I developed a variation of this process because I found the half-D1 DVD's didn't play right in some standalone players: I use gui4ffmpeg to convert the half-D1 .vob files (renamed with the .mpg extension) into full-D1 (720x480) mpeg2. It transcodes the audio from mpeg to Dolby AC3 while it's doing this. Then this .mpg file is input into DVDStyler, producing good full-D1 DVD's.

What happens to the empty NAV packets during the ffmpeg processing? Are they retained? Are they needed? Do they become irrelevant? Are they re-generated?

Inquiring minds want to know

[borax]

During transcode the empty NAV packets are lost (transcoding involves demultiplexing).
I don't use gui4ffmpeg, but I assume it can either output the elementary streams (then you can remultiplex them with mplex and the - f 8 option the include empty NAV packets if dvdstyler can use ready multiplexed material only), or maybe ffmpeg can also be configured to output a multiplexed stream with (new) empty NAV packets. As your transcoded mpeg works, this is probably the default (the recreation of the empty NAV packets).

[Lester Burnham]

During transcode the empty NAV packets are lost (transcoding involves demultiplexing).
I don't use gui4ffmpeg, but I assume it can either output the elementary streams (then you can remultiplex them with mplex and the - f 8 option the include empty NAV packets if dvdstyler can use ready multiplexed material only), or maybe ffmpeg can also be configured to output a multiplexed stream with (new) empty NAV packets. As your transcoded mpeg works, this is probably the default (the recreation of the empty NAV packets).

I'm pretty sure you can do this with ffmpeg - although not sure if it does it by default.

[dlflannery]

During transcode the empty NAV packets are lost (transcoding involves demultiplexing).
I don't use gui4ffmpeg, but I assume it can either output the elementary streams (then you can remultiplex them with mplex and the - f 8 option the include empty NAV packets if dvdstyler can use ready multiplexed material only), or maybe ffmpeg can also be configured to output a multiplexed stream with (new) empty NAV packets. As your transcoded mpeg works, this is probably the default (the recreation of the empty NAV packets).

Thanks borax and Lester Burnham for your quick and informative replies

Gui4ffmpeg tells you exactly what command line arguments it is passing to ffmpeg, and allows you to insert additional ones. DVDStyler produces a log display of what it does too. Thus I can probably tell a lot from looking at these.

I have also saved from VideoReDo as elementary streams then used gui4ffmpeg to transcode just the audio from mpeg to AC3. DVDStyler can input these elementary streams. I'm sure it is then calling mplex -- will check to see what options it uses for mplex.

Is there a utility that inspects video files and tells you whether NAV packets are present and whether they are empty or populated? (gspot?)

[borax]

Is there a utility that inspects video files and tells you whether NAV packets are present

I don't know a 'utility' for this, but yes, my Gui for dvdauthor does it. Maybe dvdstyler or dvdauthorgui as well. The info is not very usefull, except you work with dvdauthor.

... and whether they are empty or populated?

I've never cared about it, as these get 'rewritten' during authoring with dvdauthor in any case.

[dlflannery]

Is there a utility that inspects video files and tells you whether NAV packets are present

I don't know a 'utility' for this, but yes, my Gui for dvdauthor does it. Maybe dvdstyler or dvdauthorgui as well. The info is not very usefull, except you work with dvdauthor.

... and whether they are empty or populated?

I've never cared about it, as these get 'rewritten' during authoring with dvdauthor in any case.

Borax, what does your Gui for dvdauthor do if it detects an input video has no NAV packets? Apparently (based on posts I've seen many places) DVDStyler needs the empty NAV packets "because it uses DVDAuthor". Your program also uses DVDAuthor. Does it also need the NAV packets? Or does it add them (if not already present) before calling DVDAuthor?

[borax]

Yes it also needs the NAV packets. It will only tell you when there are no NAV packets in a multiplexed stream. In this case you have to demux the file(s) and either use the elementary streams or multiplex by your own with NAV packets included.
Another tool: My chaptereditor ChapEditGFD can also detect NAV packets (it will report MuxOK=1 if NAV packets are found). It is probably the 'utility' you are searching, as it only has 0.3 MB size, supports drag&drop from windows explorer or similar filemanager...

[dlflannery]

Yes it also needs the NAV packets. It will only tell you when there are no NAV packets in a multiplexed stream. In this case you have to demux the file(s) and either use the elementary streams or multiplex by your own with NAV packets included.
Another tool: My chaptereditor ChapEditGFD can also detect NAV packets (it will report MuxOK=1 if NAV packets are found). It is probably the 'utility' you are searching, as it only has 0.3 MB size, supports drag&drop from windows explorer or similar filemanager...

Thanks Borax. My "inquiring mind" is slowly learning.

I'm beginning to appreciate that VideoReDo is more than "just an MPEG editor" since it can either save as elementary streams or as .vob with the (empty) NAV packets multiplexed in (and it does anything it does fast).

BTW I hear that VRD is developing a DVD authoring plug-in. Do you have any idea whether they are cooperating with one of the existing free or commercial authoring software teams?

[borax]

...VRD is developing a DVD authoring plug-in

No idea. You should ask in the VRD forum. I don't use VRD myself, as 99.9% of my video material is capured from DVB-S as transport streams, and there is no better couple of apps than projectx + mpeg2schnitt/cuttermaran for such streams.

[Lester Burnham]

...VRD is developing a DVD authoring plug-in

No idea. You should ask in the VRD forum. I don't use VRD myself, as 99.9% of my video material is capured from DVB-S as transport streams, and there is no better couple of apps than projectx + mpeg2schnitt/cuttermaran for such streams.

With the greatest respect - and I do have a lot of respect for you, Borax - I looked and played with mpeg2schnitt and cuttermaran, before eventually buying VideoReDo.

And at first, that was mainly for just captures using a Hauppauge PVR-USB2 from digital satellite. There was a commerical editor bundled with the Hauppauge PVR box - nanopeg editor. I had so much grief trying to use it, I tried numerous freeware and payware editors, before finally stumping up the modest amount for VideoReDo.

Out of all the packages I use for video work - that's the only one I've bought - the rest are freeware.

[borax]

Ok, I will give it a try.

[dlflannery]

Ok, I will give it a try.

I am happy that my novice-question thread has provided a forum for one expert to convince another to try VideoReDo 8)

Thanks to both of you for your discussion.

[Lester Burnham]

Ok, I will give it a try.

I am happy that my novice-question thread has provided a forum for one expert to convince another to try VideoReDo 8)

Borax is the expert, here - I'm just an enthusiastic amateur.

And I didn't mean it to be some kind of persuasion to look at VideoReDo, per se, either - just that I tried the other two editors that Borax had mentioned - and they are very good, especially given that they're freeware.

It's just that after looking at all the editors at the time - and bearing in mind, my requirements were really trimming TV adverts from captures, prior to authoring to DVDs - I ideally wanted something frame accurate, that was fast and didn't re-encode. After looking at numerous, including the two Borax mentioned, and also including a commercial (abeit flawed version) bundled with my PVR box, I eventually selected VideoReDo as the one that met my personal needs best.

[dlflannery]

During transcode the empty NAV packets are lost (transcoding involves demultiplexing).
....... or maybe ffmpeg can also be configured to output a multiplexed stream with (new) empty NAV packets. As your transcoded mpeg works, this is probably the default (the recreation of the empty NAV packets).

I've done experiments that verify gui4ffmpeg does exactly what you say. Whether the input is mpeg2 without NAV packets or .vob with empty NAV packets, it takes exactly the same processing time and produces apparently identical outputs (D1 with AC3 and empty NAV packets). The details of my experiments are found in this ***Post***

Also, if you input a MPEG2 without (empty) NAV packets to DVDStyler, it will demux (presumably to insert the NAV packets). But this almost doubles its process time. I haven't tested how good a job it does on the remux'ing. It uses rmux I believe.

Saving an mpeg2 from VRD as VOB (with empty NAV packets) costs very little. The file is a percent or two larger and perhaps the VRD processing time is slightly longer. (VRD is so fast -- who cares?). Thus I have decided to adopt VOB output as my standard since the NAV packets cost little and (depending on the downstream process) can save a lot of time.

[Lester Burnham]

During transcode the empty NAV packets are lost (transcoding involves demultiplexing).
....... or maybe ffmpeg can also be configured to output a multiplexed stream with (new) empty NAV packets. As your transcoded mpeg works, this is probably the default (the recreation of the empty NAV packets).

I've done experiments that verify gui4ffmpeg does exactly what you say. Whether the input is mpeg2 without NAV packets or .vob with empty NAV packets, it takes exactly the same processing time and produces apparently identical outputs (D1 with AC3 and empty NAV packets). The details of my experiments are found in this ***Post***

Also, if you input a MPEG2 without (empty) NAV packets to DVDStyler, it will demux (presumably to insert the NAV packets). But this almost doubles its process time. I haven't tested how good a job it does on the remux'ing. It uses rmux I believe.

Saving an mpeg2 from VRD as VOB (with empty NAV packets) costs very little. The file is a percent or two larger and perhaps the VRD processing time is slightly longer. (VRD is so fast -- who cares?). Thus I have decided to adopt VOB output as my standard since the NAV packets cost little and (depending on the downstream process) can save a lot of time.

And that's exactly why I save as type "VOB" from VideoReDo, too. Costs very little at all in terms of output size, or processing time. And the same mpeg file can be used by everything I want to use it with. And it's suitable input to my choice of authoring package: GUI_for_dvdauthor (thanks Borax!).