MP4 Problem

[Nitro89]

I converted my MPEG2 video to MPEG4 using Avidemux, but when I play it back, there is only video, no audio, using k-lite codec pack, in the ffdshow configuration menu, I disabled the h.264/avc video decoder and the now the audio works, but the video doesn't. When converting my video, the audio output was AC3.

[Baldrick]

Codec packs=NO.
ffdshow, ac3filter, haali media splitter=YES.



Does it work in vlc?

[Nitro89]

what's wrong with codec packs?

no, it doesn't work in vlc.

[poisondeathray]

I converted my MPEG2 video to MPEG4 using Avidemux, but when I play it back, there is only video, no audio, using k-lite codec pack, in the ffdshow configuration menu, I disabled the h.264/avc video decoder and the now the audio works, but the video doesn't. When converting my video, the audio output was AC3.

MPEG4 could mean about 20 different things, including .mp4 container, h.264, XviD, DivX, AAC audio... can you be a bit more specific?

What settings did you use for conversion?

What does mediainfo say about your output file?

[Nitro89]

I cropped, trimmed and resized my video. I converted it to MPEG4 H264/AVC with AC3 as audio. I use Gspot for my media info, it can't identify my video codec but identify my audio, it states AC3. Under the description, it does say MP4.

[Nitro89]

Codec packs=NO.
ffdshow, ac3filter, haali media splitter=YES.



Does it work in vlc?

the codec pack contains ffdshow, AC3 Filter and Haali Media Splitter, I even uninstalled K-Lite, installed those codecs seperately and still no luck.

[poisondeathray]

The problem with codec packs is when you are trying to troubleshoot, you have no idea what is causing the problem because you have so many things installed that might be a contributing factor.

Mediainfo is usually than gspot at parsing info, give it a shot.

I doubt this is the cause, but if you are using SVN build 3794 for avidemux, it is still using x264 r816 which gives problems. You can look in the avidemux directory for a text file called "build info." This is fixed in x264 r818, but avidemux has not be updated yet.

When you trimmed, did you cut on keyframes?

**Try using .mkv as the container, because AC3 audio is not compatible in your .mp4 container. Otherwise use mp3 or AAC audio in the .mp4 container

[Nitro89]

what are the keyframes and do I avoid cutting them or do I cut them?

[poisondeathray]

what are the keyframes and do I avoid cutting them or do I cut them?

You get problems with your output video you don't cut on keyframes (with any editor, not just avidemux). In avidemux use the "<<" and ">>" to move to keyframes, and the mark in/mark out to select. If you mouse over the buttons, it tells you this.

But I bet your problem was AC3 in .mp4

Here is the technical explanation for keyframe from wikipedia:
http://en.wikipedia.org/wiki/Keyframe

In video compression, a key frame, also known as an Intra Frame, is a frame in which a complete image is stored in the data stream. In video compression, only changes that occur from one frame to the next are stored in the data stream, in order to greatly reduce the amount of information that must be stored. This technique capitalizes on the fact that most video sources (such as a typical movie) have only small changes in the image from one frame to the next. Whenever a drastic change to the image occurs, such as when switching from one camera shot to another, or at a scene change, a key frame must be created. The entire image for the frame must be output because the visual difference between the two frames is so great that the new image cannot be reproduced incrementally from the previous frame.

Because video compression only stores incremental changes between frames (except for key frames), it is not possible to fast forward or rewind to any arbitrary spot in the video stream. That is because the data for a given frame only represents how that frame was different from the preceding frame. For that reason it is beneficial to include key frames at arbitrary intervals while encoding video. For example, a key frame may be output once for each 10 seconds of video, even though the video image does not change enough visually to warrant the automatic creation of the key frame. That would allow seeking within the video stream at a minimum of 10 second intervals. The down side is that the resulting video stream will be larger in size because many key frames were added when they were not necessary for the visual representation of the frame.

[Nitro89]

thank you.

With Avidemux, where does it show the fps, once I converted one of my videos at 23.976fps, the output file became 23.952fps.

[poisondeathray]

If you push the button to the right of the save button, it tells you the file information. If you mouse over any of the buttons, they tell you the function.

Avidemux shouldn't touch the original fps, unless you enter the "assume fps" filter, or choose video=>frame rate. I suggest using avisynth if you do any frame rate conversions, because you tend to get audio/video sync problems using simple solutions.

[Nitro89]

Just to be clear, you DON'T cut ON the keyframes, you're allowed to cut anywhere else, is that right? I didn't understand your earlier post where it said "You get problems with your output video you don't cut on keyframes".

[poisondeathray]

Sorry for the bad wording.

You should navigate by using keyframes, and cut on keyframes.

[Nitro89]

I cut my video so that my first frame is my key frame "0" and my final frame is "152576", is that correct?

Also I noticed that my DVD ripped video's final key frame wasn't the final frame, is that right?