VDH downloads incorrect video and audio streams (2x video, no audio, wrong resolutions...) on some sites

[JZxx1]

Your question

On some sites, specifically aktualne.cz but also others, VDH started sometime in 2025 to incorrectly handle various video and audio streams.

E.g. On chosen 1080p resolution it downloads 240p video
On 720p resolutions downloads 360p
On 480p resolutions downloads a file with two video streams, 1080p and 360p, but without any audio :)

Can this be fixed please ? YT-DLP downloads these videos without issues and I can download them manually via ffmpeg also quite fine (it's just much more work), so it must be a bug in VDH I think. Maybe it doesn't parse manifest right ? Otherwise great tool, thanks guys! I like how quick and easy to use it is.

Short example video here, but none of the videos on that site works
https://video.aktualne.cz/den-v-60-sekundach/nejdulezitejsi-zpravy-dne-v-jedne-minute-streda-30-rijna/r~f2b20f8896d611efae9c0cc47ab5f122/

Probably similar or same issue - unsolved, though there is some longer workaround:
#1628

Addon & CoApp version and details

version: 9.5.0.2
target: mozilla
channel: stable
lang: en-US
coapp: {"found":true,"path":"C:\Program Files\DownloadHelper CoApp\vdhcoapp.exe","version":"2.0.19","new_version":false}
license: {"unset":true}
platform: x86-64 win
UA: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:142.0) Gecko/20100101 Firefox/142.0
{
"privacy_accept": true,
"view_options": {
"all_tabs": false,
"low_quality": false,
"sort_by_status": true,
"sort_reverse": false,
"show_button_clean": true,
"show_button_clean_all": false,
"show_button_convert_local": false,
"hide_downloaded": false
},
"use_sidebar": true,
"open_count_store": 1,
"successfull_dl": 11
}

[GrampaWildWilly]

I do not work for VDH. I am just another user. Also, please read #2214.

You say you've downloaded this with ffmpeg. That tells me I can be a bit terse about my explanation. When I went to your Czech web page, the Firefox Network Monitor (in the Dev Tools) showed me not an HLS master manifest but a DASH master manifest, not an M3U8 but an MPD. VDH has been known to have problems with DASH. You say you downloaded it & it had no audio. I tried to download the 1920x1080 variant & I got a 640x360 variant. But I did get audio. In cases where I have not gotten audio, the file actually did have the right resolution video but the file actually had TWO video tracks. That's right, instead of a video track & an audio track it had a video track & a video track. Apparently, that is something you have also observed. When I have played such a file in VLC, it has played the video in 2 resolutions simultaneously on my 2 monitors. I suppose if you have only one monitor this won't happen. My speculation has been that VDH does not interpret MPDs properly. It thinks the video is in one place & the audio is in another. If instead of that other place containing audio it contains video, VDH goes ahead & downloads the video erroneously thinking it's audio. You can verify this by running ffprobe on the file on your system after you download it.

Still, that doesn't explain why I got video & audio instead of video & video. That is rather mysterious.

If you run ffprobe on the MPD here, you'll see there's 6 video resolutions to choose from & 2 audio resolutions. VDH actually managed to pick the audio with the higher bit rate in my case. I have a (completely unsubstantiated) hunch that because the higher resolution audio is the very last stream listed by ffprobe that somehow VDH picked that one. I don't have any hunches why VDH picked the 640x360 video. It's actually the second resolution listed by ffprobe. This is all a complete mystery to me. I did download this with ffmpeg myself & this is what I got:

ff mp4 Log.txt

That's the 1920x1080 resolution video, the highest one in the manifest, & the audio with the higher bit rate, also the "best" one in the manifest.

Until VDH is fixed, this is what you have to do.

[JZxx1]

Yes, fully agree 100%. Btw the file with 2 video tracks also opens in 2 separate VLC windows on 1 monitor.

I'm actually using YT-DLP as a workaround for similar sites, it's not a one-click solution like VDH, but still a few seconds job (just copy url and drop it onto ytdlp.exe). The workaround with renaming m3u8 is a pain for me...

[GrampaWildWilly]

That trick of changing the URL from .mpd to .m3u8 is something that I believe is not a general solution. For some reason, some sites have a stealth HLS manifest that they don't send to your client web browser by default. But when you change the file name, poof magic, there it is. I believe this does not work on all sites. It's something to remember to try, but you shouldn't expect it to always work. If I were running a web site, I wouldn't keep both a DASH & an HLS master manifest for any content. I'd have one or the other but not both. So the rename trick wouldn't work on a site I ran. I suppose it's good that I don't know enough to be able to actually run a web site. It just seems like duplicate work & a waste of disk space to maintain a shadow manifest for each video on a web site.

[Mattmjs]

I read somewhere online that said some apple devices don't support dash streaming such as ipads and iphones.
I don't know whether that is true or not.

Maybe that is the reason they have a HLS version on some sites. HLS was invented by Apple to run on apple devices because they said we're not using Adobe Flash. The Hotstar site ( indian streaming service ) was using dash by default.
I found by switching the user agent to iphone or Mac to my surprise served a HLS version. That was a workaround for someone
using Hotstar.

[GrampaWildWilly]

I've just been reading up on things at a site called ottverse.com. Looks like a valuable resource. In any case, it does say there that Apple devices of all kinds do not understand DASH. Apple invented HLS so they feel that HLS is all you need. They do not support DASH. DASH apparently was cooked up by a consortium of other organizations, apparently in competition with HLS, I assume to provide something that is not proprietary. But HLS is certainly no longer proprietary, if it ever was. However, many web sites choose HLS for the explicit purpose of including Apple devices in their target audience. I gather DASH offers a lot of options that HLS does not. MPDs are certainly way more complex than M3U8s. I imagine only sites with the deepest pockets offer both HLS & DASH. If I understand things correctly, at the server, the source for transmitting content via HLS is different from the source for transmitting content via DASH. So in order to support both, a site would have to basically duplicate everything. Like I say, that takes relatively deep pockets. So you typically won't see both on the same web site. That makes it very surprising that this trick of changing .mpd to .m3u8 sometimes works. I wonder if some day VDH will offer both HLS & DASH download options on sites where it's available. In the end, the results of downloading via HLS & DASH are the same. It's an MP4 or MKV or whatever & there are no residual artifacts in the content to say how it was downloaded. VLC plays them all just fine.

[GrampaWildWilly]

More learning. I put this question to Google:

How is data packaged for HLS transport different from data packaged for DASH transport?

Then I clicked the AI dive deeper button. It appears that the differences between the packaging for HLS & DASH are disappearing. It looks like the trend is toward making it a lot cheaper to support both transport protocols on the same web server. Still, DASH allows for a lot more possibilities. HLS is still controlled by Apple & DASH still doesn't work on Apple devices without shim software. But apparently such shim software does exist so Apple devices can support DASH if you're adept enough at installing the necessary additional software. None of which I have any experience with. I've never owned or even used anything made by Apple . . . except for an iPod I bought about 20 years ago. Come to think of it, I haven't used the iPod in a few years. I may never use it again. I got the iPod to listen to music of my choosing at the gym while I worked out. I've got other ways of doing that with my Android phone. An apple a day may be good for your health but I have no Apples on any day.

[Mattmjs]

I brought that up in #2042 , probably it will be fixed in the next release. Don't know when though.

[TEOL85]

All the devs need to do is make the YouTube mode a fully fledged YT-DLP GUI then everything with YouTube would be solved wouldn't it? It's open source the team should have done it since it first come out they are too lazy these days though.

9.5.0.2 is what I'm still on at the moment becasue the new V10 YouTube is rumoured to be worse than the version I'm using which only stops working when the ads are blocked and it needs and advert played to get anymore but is V10 added TY-DLP I might be interested in the update as it would be YouTube perfection in my VDH again at last with the 48000 khz audio format I waited for years finally getting in there.