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I have a flash (flv) video file that plays fine in VLC media player (version 0.9.4 on Windows XP). When I try to convert it to an mp4 file (with MPEG-4 encoding), I get a file that has only audio. No corrupted video or anything, it's really just audio: the file is about 2 MB instead of the original 50.

Original video: Codec VP6F, resolution 576x324, file type .flv, with 1-channel 16-bits mp3 audio at 22050 Hz.
Desired output: MPEG-4 .mp4 file with resolution 480x270 (i.e. the same proportions as the original, but fewer pixels), and I don't care about the other parameters as long as it works.

I'll tell you exactly what I do. I don't know if this is right, due to the almost complete lack of definitive documentation on version 0.9.x.

1. I open the player without any video in it.
2. I go to Media... Advanced open file (or Media... Convert/Save or Media... Streaming).
3. In the dialog box I select the file and click the arrow next to "Open" and select "Stream". It sounds more logical to select "Convert", but several tutorials seem to prefer "Stream" -- and by the way, with "Convert" the results are no better.
4. Under Outputs, I check File and enter a filename that ends with mp4. I click "Save" (though I'm not ready to save anything yet).
5. Then under Profile I select this:
   Encapsulation: MP4
   Video codec: Video; MPEG-4
   Audio codec: Audio; MPEG 4 Audio (AAC)
6. Then I go down to the string at the bottom and insert width=480,height=270, in the transcode parameters. The output string then looks like this:
   :sout=#transcode{vcodec=mp4v,vb=800,width=480,height=270,scale=1,acodec=mp4a,ab=128,channels=2}:duplicate{dst=std{access=file,mux=mp4,dst=C:\Documents and Settings\jim\Desktop\outfile.mp4}}
7. I click "Stream" (or "Save").

A few things I have tried:

• This tutorial suggests that the width and height settings must first be changed deep down in the advanced preferences. I don't know if it is true, but I did it anyway -- no luck.
• This article says that the output string should be:
  :sout=#transcode{vcodec=mp4v,vb=1024,scale=1,height=240,width=320,acodec=mp4a,ab=128,channels=2}:duplicate{dst=std{access=file,mux=mp4,dst=%1.mp4}}
  which is very close to what I have -- but I gave it a try and it doesn't make a difference.

What's going on? Is VLC media player supposed to be able to do this at all?

Open Tools -> Messages... (set Verbosity to 2) before you try the conversion and when it is done, paste the messages here.

new-user, i have the same problem can anyone help me.
i'm trying to convert video files into mp4 format.
thanks

As VLC_help said post messages.

I tested an FLV to MP4 conversion, and this may be the issue: i.e. the output video is of zero resolution.

Arite.

Open Tools -> Messages... (set Verbosity to 2) before you try the conversion and when it is done, paste the messages here.

Here is the log. It's quite big -- I hope it scrolls.

Do you have a sample FLV you could upload (or a link to source of the FLV file)?

Arite.

Well, I can tell you that another ffmpeg-based encoder managed to transcode the file. With the parameters this gave an output video that works fine. The output of the process was: Actually I would prefer to be able to do this with VLC Media Player; I really like the player and I prefer to have an all-in-one solution. If the log messages gave any clues to settings that might have helped, I would still be interested to know.

^ Those messages are from FFmpeg presumably - post VLC's messages ("Tools >> Messages..." and set "Verbosity Level" to 2).

Arite.

^ Those messages are from FFmpeg presumably - post VLC's messages ("Tools >> Messages..." and set "Verbosity Level" to 2).

Arite.

Yes, I posted the log from VLC two posts above that one.

main error: cannot add a new stream (unsupported while muxing to this format). You can try increasing sout-mux-caching value
Sounds like a bug. Have you tested 1.0.0 test builds?

main error: cannot add a new stream (unsupported while muxing to this format). You can try increasing sout-mux-caching value
Sounds like a bug. Have you tested 1.0.0 test builds?

No, do you think that would help? I mean, has the team solved a bug like this for the 1.0.0 builds? If nobody has submitted this problem for debugging, I guess it could only have been solved by accident...

Worth trying a nightly build anyway:
http://nightlies.videolan.org/

Sout might not work very well though ATM - try via commandline if GUI does work properly with transcoding.

Arite.

Worth trying a nightly build anyway:
http://nightlies.videolan.org/

Sout might not work very well though ATM - try via commandline if GUI does work properly with transcoding.

Arite.

OK, I tried with the latest nightly (0.9.9-rc2-20090321-0104) and got the same result: audio only.

I also tried with the command line and got the same result. But I used a command I found at the VideoLAN wiki, which involves a sout string (vlc -vvv "Infile.flv" :sout="soutstring"). If you say sout might not work at the moment, do you mean there is an alternative way to use the command line?

Well the Steam Output section of the GUI has be reworked for 1.0.0 and (as of a few days/weeks ago) didn't work too well - I think it has improved now though. If it doesn't then yes, try the commandline. The syntax: Should work fine (where SOUT_STRING is the sout string minus the ":sout=" bit - double hyphens can be more reliable than colons hence the "--sout").

Cheers, Arite.

Well the Steam Output section of the GUI has be reworked for 1.0.0 and (as of a few days/weeks ago) didn't work too well - I think it has improved now though. If it doesn't then yes, try the commandline. The syntax:

Code: Select all

vlc -vvv INPUT --sout "SOUT_STRING"

Should work fine (where SOUT_STRING is the sout string minus the ":sout=" bit - double hyphens can be more reliable than colons hence the "--sout").

Cheers, Arite.

With that form of the command, the result is the same again (with both the current version and the nightly build). Here is the log from the nightly: Again it makes the suggestion "You can try increasing sout-mux-caching value". Is there a way to increase that value?

And is there a version 1.0.0? What I used was 0.9.9-RC2.

VLC 1.0.0-git builds can be found in the "trunk" directories of the nightlies.

The set the sout-mux-caching value just add e.g.: Where 5000 is the caching value in ms.

Arite.

VLC 1.0.0-git builds can be found in the "trunk" directories of the nightlies.

The set the sout-mux-caching value just add e.g.:

Code: Select all

--sout-mux-caching 5000

Where 5000 is the caching value in ms.

Arite.

Well, the new version (1.0.0-git-20090316-2305) did it, sort of.

First of all, adding the --sout-mux-caching 5000 bit didn't help in the 0.9.x versions. And using the GUI or the command line in 1.0.0 gave the same error as before, with the sout-mux-caching problem and an audio-only output file.

But using 1.0.0 from the command line and with the --sout-mux-caching 5000 switch gave a file with video, in the right dimensions. The only problem: out of a 50 MB input file it created a 795 MB output file. For comparison: the ffmpeg method from my earlier post made it 35 MB.

I guess that's it for the moment, I will keep that ffmpeg-frontend around for when VLC can't transcode something. Arite, thanks for your help.

The only problem: out of a 50 MB input file it created a 795 MB output file.

Bitrates are too high or wrong codecs are used.

Bitrates are too high or wrong codecs are used.

The sout string I specified on the command line contains these bitrate/codec parameters:

• vcodec=mp4v
• vb=800
• acodec=mp4a
• ab=128

Maybe version 1.0.0 has defected codecs or some bitrate defaults I can't override?

When playing the video in VLC does "Tools >> Codec Information..." read the same info/values, and in the "Statistics" tab are the bitrates around the same?

Arite.

When playing the video in VLC does "Tools >> Codec Information..." read the same info/values, and in the "Statistics" tab are the bitrates around the same?

Arite.

I had already deleted the 1GB video, so I decided to recreate it using the same command line string and the same version (the 1.0.0-git). Only this time I quit all other programs before doing it. It gave me a 30 MB mp4 file....

I guess this means that some of the trouble with VLC was due to a lack of processing capacity or RAM. Strangely, the new video has just one audio channel, whereas I specified two. EDIT: this seems to depend on the player... Quicktime says it's mono and 1 channel, VLC did that too, but after I deleted the VLC cache (%appdata%\vlc) it now says there are two. ??

The Codec information about the result is:
Audio:
Codec mp4a (OK)
1 channel (I specified channels=2) -- but 2 channels after cache deletion
22050 Hz (OK) -- now: 44100 Hz
16-bits (OK)
Bitrate 352 kbps (I specified ab=128)
-- now: AAC extension: SBR
Video:
codec mp4v (OK)
480x270 (OK)
frame rate 15 (OK)
The video bitrate is about 513 kbps (I specified vb=800).

The quality is good, considering the actual video bitrate.

Interesting findings, though I don't know what to make of all this.

At least everything seems to be alright now. The summary: quit all other programs, use version 1.0.0 and add --sout-mux-caching 5000 to the command. In case of audio playback problems, delete %appdata%\vlc. Thanks for the help!

There is tool called Mediainfo which should tell you more about mediafiles.

There is tool called Mediainfo which should tell you more about mediafiles.

Mediainfo tells me this:
Audio
ID : 1
Format : AAC
Format/Info : Advanced Audio Codec
Format version : Version 4
Format profile : LC
Format settings, SBR : No
Codec ID : 40
Duration : 7mn 58s
Bit rate mode : Variable
Bit rate : 38.0 Kbps
Maximum bit rate : 64.9 Kbps
Channel(s) : 1 channel
Channel positions : C
Sampling rate : 22.05 KHz
Resolution : 16 bits
Stream size : 2.17 MiB (7%)

That leaves me with two mysteries:

1. Why does VLC convert to one-channel audio when asked to make two channels
2. Why does it say there are two channels when there is only one

You have prolly found some bugs. Could you share your sample file and your transcoding options, so I can open trac tickets?

You have prolly found some bugs. Could you share your sample file and your transcoding options, so I can open trac tickets?

OK, I couldn't find a link to the original file, and uploading 50 MB will not make anyone happy, but I've taken a 7 second clip (473 kB) and it has essentially the same problem. The output of VLC (388 kB) has 1 audio channel according to Mediainfo, and two channels according to VLC Media Player (both versions 0.9.x and 1.0.0-git). Do I attach this to a PM to you or something?