I have problem that, Im downloading just header of file ( 8000 bytes or I can take more ). Then from those bytes array Im trying to identify it and get height of video.
When for AVI is simple and I see it then for mp4 I can find this resolution.. Anyone familiar with it ? Thanks
Ive found nice source code which helped me:
https://github.com/sannies/mp4parser/blob/c869d076e9cd42aba5a3e35d88827610dec6ca15/examples/src/main/java/com/google/code/mp4parser/example/GetHeight.java
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My MP4 file issue is a bit complicated, so I have created a very simple scenario to help me diagnose it step by step.
I can create a working MP4 file that works flawlessly. The following is its structure shown by Mp4Explorer:
For debugging purpose, I removed the media data box mdat, and al stts, stsz,stss, stsc, stco boxes and kept everything else the same. This means the MP4 file has no media data. It just has some metadata.
This file is named error.mp4. If I run:
ffprobe "error.mp4"
I get the following error:
[mov,mp4,m4a,3gp,3g2,mj2 # 00000286e763ef00] Could not find codec parameters for stream 0 (Video: h264 (avc1 / 0x31637661), none, 1280x800): unspecified pixel format
Consider increasing the value for the 'analyzeduration' (0) and 'probesize' (5000000) options
Could anyone shed some light on this error? Why is it "Could not find codec parameters for stream 0"? If I remove the video track and leave the audio track as is, ffprobe will be happy with no errors.
I have extracted the audio data from .m4a file using mp4v2 library (sample-by-sample). Does this library have function that decodes the data? Anybody with experience with this library and can provide some help?
The documentation says:
MP4ReadSample function reads the specified sample from the specified track.
Typically this sample is then decoded in a codec dependent fashion and
rendered in an appropriate fashion.
I am interesed in decoding the output.
Thanks in advance.
You tagged MP4(video data) and M4A(audio data). Since you are extracting from M4A, I can only imagine you actually have either AAC or MP3 audio data.
Each extracted sample (bytes) is audio frame.
To make a playable MP3 file : Simply join all MP3 frames' bytes together. Save as .mp3 to play later.
To make a playable AAC file : For each AAC frame, first create an ADTS header (7 bytes) followed by that frame's data. You can test your header bytes here (site shows what your byte values mean). When all your AAC frames each begin with an ADTS header, simply save as .aac to play later using some audio payer code.
I have researched everything and the answer is NO. There is no decoder in mp4/mp4v2 libraries. One has to use some other library to do that.
I'm trying to use GDCL MP4 Muxer with my RTSP Source Filter. They work fine together except after stopping the graph, muxer doesn't finilize the file and write the reqiured tables to the end of file via file writer (some parts are written starting from moov but not the time table values). When I try another RTSP source filter (which I don't have its source codes), table values are created with GDCL MP4 Muxer.
But when I try Elecard's MP4 Muxer, it works fine with my RTSP Source Filter. So, there is an incompatibility. I examined GDCL's source codes but couldn't find what it was expecting from me. I already calculate and set timestamp values to samples using SetTime method. But GDCL still doesn't finilaze file. Is it caused by missing information or missing signal when graph stops? What can be the problem, any ideas?
One thing you should be aware of regarding Geraint's MP4 Mux is that it is checking incoming media samples to have both start and stop time. You might be having only .tStart/AM_SAMPLE_TIMEVALID which still makes sense for video, but this would be a problem.
So the samples have to have stop time, or you need to fix this in multiplexer code.
A typical symptom for the problem is that generated files are empty or of zero duration.
I am having a problem when creating an avi file using Matlab. My aim is to use an edge filter on an entire video and save the file as an avi. The filter works fine, my problem is the writing of the avi file.
My code:
vidFile = VideoReader('video.avi');
edgeMov = avifile('edges','fps',30);
for i = 1:vidFile.numberofframes
frameI = read(vidFile,i);
frameIgray = rgb2gray(frameI);
edgeI = edge(frameIgray,'canny',0.6);
edgeIuint8 = im2uint8(edgeI);
edgeIuint8(:,:,2) = edgeIuint8(:,:,1);
edgeIuint8(:,:,3) = edgeIuint8(:,:,1);
edgeMov = addframe(edgeMov,edgeIuint8);
end
edgeMov = close(edgeMov)
When the loop finishes and the avifile is closed, I go to play the video and it says "Windows Media Player encountered a problem while playing this file". I've also tried, without success, Media Player Classic and VLC which lead me to believe that the problem must be the file itself. Using GSpot I checked the file and it said that the AVI header is corrupt.
Retrying the loop again returned exactly the same problem. What's confusing me is when I run the loop for a smaller number of frames, 30 for example, the video writes fine and I can watch it. The size of the video I am trying to convert is in excess of 1000 frames so I don't know if size is a problem?
Any help would be greatly appreciated, thank you.
I've used the following to create AVI
edgeMov = avifile('video.avi','compression','Indeo5','fps',15,'quality',95);
Give it a try.
I am trying to read a movie in avi format. But it's giving me the following error:
xyloObj = mmreader('1.avi',[1 5]);
??? Initialization failed. (No combination of intermediate filters could be found to make the connection.)
Error in ==>
mmreader.mmreader>mmreader.init at 423
obj.MMReaderImpl = audiovideo.mmreader(fullName);
Error in ==>
mmreader.mmreader>mmreader.mmreader at 133
obj.init(fileName);
Kindly help me
The likely source of the error is that you are missing the proper codec required to read the given AVI file. Apparently, this can often happen when using 64-bit versions of MATLAB on 64-bit Windows platforms. There are a number of solutions you can try given in this technical support documentation from the MathWorks.
First, can you play it with another application (such as VLC player, Windows Media Player, QuickTime, etc.) on your computer?
If yes, go to gnovice's link.
If no, go get the GSpot codec information tool which is very useful for determining which codec you need. Download the codec and make it work with a video player, then Matlab.
This pdf explains how to solve your problem. Or just use:
vid = aviread('Vid261.avi');
vi = frame2im(vid(1)) ;