I am using the SampleGrabber filter to get the frames of an AVI file and alter them before writing them to another (new) AVI file using the File writer filter.
The problem that I am facing is that the new AVI file size is greater then the original file. I removed the SampleGrabber filter thinking that it might be my code causing the problem, but still the new file size is greater then the original file. I tested it with graphedit.
The filters used were File reader->AVI Splitter->AVI Mux->File writer.
I really want to preserve the file size. Is there any other filter or property that I have to set. At the moment I am only adding the Filters in GraphBuilder and rendering the file.
I am using DirectShowLib.Net.
I just did a quick test using
File source (async) -> AVI splitter -> AVI mux -> file writer
in graphedit and the output file always seems to come out the same size as the input for me. The only thing I can think of is that your input file might be compressed. It might be worth inspecting the input file with an app like gspot to determine that. As I understand it DirectShow will sometimes insert appropriate filters in order to make a connection, so if you're trying to connect your file source to an AVI splitter it may insert a decompressor if needed. Hope that's of some use
Related
Is it possible to add a subtitle file (srt) to an existing mkv file?
I can easily embed the srt file in a new mkv file, but it is quite time-consuming.
If it is not possible just to add a srt file to the mkw container can anyone explain why?
I’m using MKVToolNix ver. 9.5.0
Cheers
/Jonas
As suggested I found an explaining answer in a superuser group.
"It cannot just be added at the end. The srt file needs to be splitted into the individual lines and interleaved with the video and audio blocks through the whole file. The clusters and cues need to be adjusted for all tracks, headers need to be added and updated. It is a complicated process."
https://www.matroska.org/technical/diagram/index.html
I have video file split into few chunks. Split done and random file positions, but chunks are large enough.
I need to parse every part with different instances of AVFormatContext. Chunks come one after another in right order. I think there are two options here:
Being able to save and restore AVFormatContext state;
Save video file header (from first chunk) and attach it to every chunk.
I tried both but no success. First approach requires to go too deeply beyond public API of ffmpeg. With second approach I am unable to merge header with new chunk so that ffmpeg can handle it.
Can you help me with this?
Thank you.
It totally depends on the file type. MP4 for example, the header must be completely rewritten, and can not just be copied. Flv the header can probably just be copied, but MUST be split on frame boundary and not randomly. TS could do this, but you would miss a frame at the cut point.
Realistically, the file will need to be reassembled, the split correctly.
Now I used C language and ffmpeg realize a multiplex real-time audio and video to MP4 files of the program and everything works fine, but when in the process of reuse of sudden power failure, the recording is MP4 file is damaged, VLC can not play this file.
I think reason is no call to write the trailer function av_write_trailer , causing index and time stamp information lost, I use araxis merge tool compared the successful call av_write_trailer function of file and a no av_write_trailer to call the damaged files and found two different points:
1. Damaged files in the file header box number value not right
2. The damaged file no end of file.
Now I want to repair after power on my program can automatically repair the damaged files, in Google did not find effective methods.
my train of thought is in the normal recording process saves per second a damaged file is missing two information: box number and end of file, save it to a local file, when writing the MP4 file integrity delete this file after, if power off damaged, then in the next power, read the file and the corresponding information to write the damaged files corresponding position to. But now the problem is that I don't know how to save the number of box and the end of the file, I this is feasible? If possible, what should I do? Looking forward to your reply!
The main cause of MP4 file damage is due to header or trailer not written properly on the file , then , whole file become a junk data. Thus none of the media player able to play the broken mp4 file.
So,
First , broken file has to be repaired before playing the file.
there are some applications and tricks available to repair and get the data back
links are given below :
http://grauonline.de/cms2/?page_id=5 (Windows / Mac)(paid :( )
https://github.com/ponchio/untrunc (Linux based OS)(ofcourse,free!!!)
Second, Manually repairing the corrupt file using HEX editor.
Logic behind this hack :
This hack requires a broken mp4 file and good video file where both videos are captured from the same camera .Also its size should be larger than the broken mp4 file.
Open both video file in any HEX editor. Copy trailer part from good video file to broken video file and save it!Done!!
Note : Always have a backup of video file.
follow these links for detailed informations :
http://janit.iki.fi/repair-corrupted-mp4-video/
https://www.lfs.net/forum/thread/45156-Repair-a-corrupt-mp4-file%3F
http://hackaday.com/2015/04/02/manual-data-recovery-with-a-hex-editor/
http://www.hexview.org/hex-repair-corrupt-file.html
Third, Even tough MP4 file has many advantages , this kind of error is unpredictable and difficult to handle it.
Thus , Using format such as MPG and AV_CODEC_ID_MPEG1VIDEO/AV_CODEC_ID_MPEG2VIDEO (FFMPEG) may help to avoid this kind of error. The mentioned MPG format does not require any header/trailer.if there is any sudden power failure MPG file can play the file whatever frames are stored so far.
Note : there are other formats and codec also available with this kind of properties.
I have a C# app. I have 100 JPEGs (for an example).
I can easily encode this into a video file.
When it has finished encoding on the client app I FTP upload to my server.
It would be 'neater' if I could not write the video file to a disc but instead write it to a memory stream (or array of bytes) and upload via web service perhaps?
I have checked out the ffmpeg documentation but as a C# developer I do not find it natural to understand the C examples.
I guess my first question is it possible, and if so can anyone post an example code in C#? At the moment I am using the process class in C# to execute ffmpeg.
Your process method is already good, just needs adjustments:
Set StartupInfo.RedirectStandardOutput = true and StartupInfo.UseShellExecute = false.
Instead of an output file name, call ffmpeg with pipe:, which will make it write to the standard output. Also, since the format cannot be determined from the file name anymore, make sure you use the -f <format> switch as well.
Start the process.
Read from Process.StandardOutput.BaseStream (.BaseStream, so the StreamReader that is .StandardOutput doesn't mess anything up) while the process is running into your memory stream.
Read anything still remaining buffered in Process.StandardOutput.BaseStream.
Profit.
I coded a thumbnailer a while back (BSD 2-clause), that has actual code that demonstrates this. Doesn't matter if it is an image or a video coming out of ffmpeg in the end.
I'm trying to write DirectShow filter which will read file containts some xml-data at the beginning and avi video after it. I'm going open a file in the filter, skip the xml-data and begin the playback. I found in the Windows SDK the example which played BMP-file (Microsoft SDKs\Windows\v7.1\Samples\multimedia\directshow\filters\pushsource). Where can I spy out how do I read avi frames, convert ones and push it in an output pin?
Sorry for my English.
You can find AVI file specs here. But there is an easier solution: use standard AVI Splitter filter which is part of DirectShow. Just take another sample filter from SDK - Async and make it read your XML data and then act as a regular file source but reading data from your file with some shifted offset. This way all the parsing work will be done by AVI Splitter and all your filter needs to do is reading parts of file that Splitter requests.