I am working with video in Matlab, and having trouble.
I'm using Matlab R2012a on a Mac OS X 10.8.2 (Mountain Lion).
I can load a video in using VideoReader and grab a frame like so:
vid = VideoReader('movie.mp4');
pic = read(vid, 20);
imshow(pic);
However, what I see in Matlab is..
Instead of this (in VLC)..
Not only is movement being garbled (the turquoise truck) but the green truck in the background is actually gone by that frame. I'm guessing the codec is compressing the movie in such a way that Matlab isn't compensating for. However, I can't find any other video format that Matlab will accept.
The video shown is mpeg4, yuv420p. I see Matlab mentions a lot about mpeg2 being supported and AVI being the preference. I've converted the video to all sorts of formats using ffmpeg but Matlab has given the following error for every other file format:
Error using VideoReader/init (line 447)
Failed to initialize internal resources.
Error in VideoReader (line 132)
obj.init(fileName);
Any thoughts?
Got it.
Thanks to #wakjah for the tip about QuickTime. A video editor friend suggested MPEG StreamClip to convert to the QuickTime format.
This tool took my mp4 file and let me Export as QuickTime.
Sure enough, Matlab loaded it up the mov file no problem and the artifacts are gone.
Cheers.
Related
The mvhd atom or box of the original Quicktime MOV format supports a poster time variable for a timecode to use as a poster frame that can be used in preview scenarios as a thumbnail image or cover picture. As far as I can tell, the ISOBMFF-based MP4 format (.m4v) has inherited this feature, but I cannot find a way to set it using FFmpeg or MP4box or similar cross-platform CLI software. Edit: Actually, neither ISOBMFF nor MP4 imports this feature from MOV. Is there any other way to achieve this, e.g. using something like HEIFʼs derived images with a thmb (see Amendment 2) role?
The original Apple Quicktime (Pro) editor did have a menu option for doing just that. (Apple Compressor and Photos could do it, too).
To be clear, I do not want to attach a separate image file, which could possibly be a screenshot grabbed from a movie still, as a separate track to the multimedia container. I know how to do that:
Stackoverflow #54717175
Superuser #597945
I also know that some people used to copy the designated poster frame from its original position to the very first frame, but many automatically generated previews use a later time index, e.g. from 10 seconds, 30 seconds, 10% or 50% into the video stream.
I am rendering a video file from input pictures that come from a 3D engine at runtime (I don't pass an actual picture file, just RGB memory).
This works perfectly when outputting MP4 using CODEC_ID_H264 as video codec.
But when I want to create an MPG file using CODEC_ID_MPEG2VIDEO, the resulting file is simply broken. No player can play the video correctly and when I then want to concatenate that MPG with another MPG file, and transform the result MP4 in another step, the resulting .mp4 file has both videos, but many frames from the original MPG video (and only video! Sound works fine) are simply skipped.
At first I thought the MPG -> MP4 conversion was the problem, but then I noticed that the initial MPG, which comes from the video render engine, is already broken, which would speak for broken headers. Not sure if it is the system or sequence headers that are broken, though.
Or if it could be something totally different.
If you want to have a look, here is the file:
http://www.file-upload.net/download-7093306/broken.mpg.html
Again, the exact same muxing code works perfectly fine when directly creating an MP4 from the video render engine, so I'm pretty sure the input data, swscale(), etc. is correct. The only difference is that CODEC_ID_H264 is used and some additional variables (like qmin, qmax, etc.) are set, which are all specific to H264 so should not have an impact.
Also, neither avformat_write_header nor av_write_trailer report an error.
As an additional info, when viewing the codec data of the MPG in VLC player, it is not able to show the FPS, resolution and format (should show 640x360, 30 fps and 4:2:0 YUV).
I am using a rather new (2-3 months old, maybe) FFmpeg version, which I compiled from sources with MinGW.
Any ideas on how to resolve this would be welcome. Currently, I am out of those :)
Alright, the problem was not the avformat_write_header, but that I did not set the PTS value of each written video packet to AV_NOPTS_VALUE.
Once I do set it for each video packet, everything works fine.
I assumed that AV_NOPTS_VALUE was the default, as I never needed to set any special PTS value.
I have searched the web and here for answers but so far, the links are dead, the how-tos no longer work for the version I have, or there are no answers.
I have a swf animation with full sound and scripting that I'd like to convert into a video or an flv. For some reason, the site I post on screws with my timeline somehow (the timing is off, sounds no longer match up properly with the text) so I thought a video would work better.
I tried using File>Export>Export to movie to resolve this. I tried to export to an AVI. When it's scaled down to 300x400 it works just fine (though it looks like total crap). However when I export at the full size, using full colors no compression, I get this.
I'm not sure what to do with it. It's slanted with lines through it and grayscale. VLC player is the only thing that will run it too. WMP dies with errors, saying it's an invalid or corrupt format. Funny thing is, the thumbnail for the video is exactly what it should look like.
I'm not sure what to do with it. Converting it to an .flv is just fine. I have a video converter for that. I just can't get it to convert to flv or even a movie type properly.
Why is it doing this to my video? Is there something better to use to convert? Is there a good one that won't plaster a giant watermark over it?
image being totally screwed up.
Flabaco is an online SWF to video converter. To answer your questions: It's free, doesn't impose banners or watermarks.
I have a swf animation with full sound and scripting that I'd like to
convert into a video or an flv.
Flabaco converts scripted content. It preserves the frame rate (fps) & color. It's capable of generating professional quality HD content.
It doesn't convert sound. Nonetheless the converted quality is good and you might be able to get by using another video tool to add sound to the converted video.
You can use the online converter app here: www.Flash-Banner-Converter.com
PS: There are some older posts on StackOverflow related to your question. Just search SWF to video / Flabaco.
Kayo,
FLABACO (FLAshBAnnerCOnverter)
Given a sample buffer of H.264, is there a way to extract the frame it represents as an image?
I'm using QTKit to capture video from a camera and using a QTCaptureMovieFileOutput as the output object.
I want something similar to the CVImageBufferRef that is passed as a parameter to the QTCaptureVideoPreviewOutput delegate method. For some reason, the file output doesn't contain the CVImageBufferRef.
What I do get is a QTSampleBuffer which, since I've set it in the compression options, contains an H.264 sample.
I have seen that on the iPhone, CoreMedia and AVFoundation can be used to create a CVImageBufferRef from the given CMSampleBufferRef (Which, I imagine is as close to the QTSampleBuffer as I'll be able to get) - but this is the Mac, not the iPhone.
Neither CoreMedia or AVFoundation are on the Mac, and I can't see any way to accomplish the same task.
What I need is an image (whether it be a CVImageBufferRef, CIImage or NSImage doesn't matter) from the current frame of the H.264 sample that is given to me by the Output object's call back.
Extended info (from the comments below)
I have posted a related question that focusses on the original issue - attempting to simply play a stream of video samples using QTKit: Playing a stream of video data using QTKit on Mac OS X
It appears not to be possible which is why I've moved onto trying to obtain frames as images and creating an appearance of video, by scaling, compressing and converting the image data from CVImageBufferRef to NSImage and sending it to a peer over the network.
I can use the QTCapturePreviewVideoOutput (or decompressed) to get uncompressed frame images in the form of CVImageBufferRef.
However, these images references need compressing, scaling and converting into NSImages before they're any use to me, hence the attempt to get an already scaled and compressed frame from the framework using the QTCaptureMovieFileOutput (which allows a compression and image size to be set before starting the capture), saving me from having to do the expensive compression, scale and conversion operations, which kill CPU.
Does the Creating a Single-Frame Grabbing Application section of the QTKit Application Programming Guide not work for you in this instance?
Anyone know how to convert a JPEG image to MPEG still frame format? I'd love to do it in java but a linux command line process would be ok. (I saw something on code project that does this for c sharp).
I haven't done it myself but here is an overview of converting JPEG's into MPEG's. I would take a look at using FFMPEG.
Overview Link: http://electron.mit.edu/~gsteele/ffmpeg/
FFMPEG: http://ffmpeg.mplayerhq.hu/