I'm writing a simple C program to read an AVI file as input (it contains an
uncompressed video and audio stream) and produces an AVI file as output. In
both input and output files, the audio is not compressed and the codec is
AV_CODEC_ID_PCM_S16LE.
In my simple program, I call avcodec_open2()
> > With AVI files, this seems complicated since the
> > number of audio frames does not always equal the
> > number of video frames.
>
> This has absolutely nothing to do with the container.
Okay. Well I was previously told that mxf containers
will store all the audio packets that correspond
Hi. When I send messages to libav-user@ffmpeg.org that message gets added
to the libav-user archive, but the message never gets sent to the mailing list.
Nobody can see my messages unless they read the archive.
Can someone look into what is broken?
___
Sorry if this email gets sent
twice. It never showed in the archive. Yahoo
mail sux:
I wrote a libAV-based application which edits a video
file. It takes a video
file as input, along with the Edit List. The input video
file is an AVI container
and was created by ffmpeg or mencoder
Sorry if this email gets sent twice. It never showed in the archive. Yahoo
mail sux:
I wrote a libAV-based application which edits a video file. It takes a video
file as input, along with the Edit List. The input video file is an AVI
container
and was created by ffmpeg or mencoder during
I wrote a libAV-based application which edits a video file. It takes a video
file as input, along with the Edit List. The input video file is an AVI
container
and was created by ffmpeg or mencoder during the inverse-telecine step.
The Edit list contains a list of Start/Stop PTS pairs. The outp
I wrote a libAV-based C program for video editing. It takes a video file as
input and produces a video file as output. The input file is AVI container,
yuv422p pixels, and is ffvhuff compressed. I want the output file to also be
AVI, yuv422p pixels, but uncompressed video (not ffvhuff). What sh
>What you're describing
sounds like the multithreading approach that ffmpeg uses. My
>understanding: The first decode call starts a decode action which spawns a
>thread to >decode that frame. Each subsequent decode call starts a new
>action/thread, until you run >out of threads, at which point
>And issue is probably withing avi container as it
>may not add every frame into index table.
>And when seeking you never check if returned packet actually is right
>one that you need.
>
>Or it could be bug in your code how you seek in file, etc...
Sorry for the top post (again). The problem is Y
what 'cached
frames' are but nobody answered. Does anyone understand this?
Also, none of the above oddness happens if I use AVI files encoded with
no codec or with lossless JPEG, or a few other codecs.
On Wednesday, October 16, 2013 3:48 PM, Paul B Mahol wrote:
On 10/16/13, Paul
>On 10/17/13, James Board wrote:
>>>You noted it wrong. Huffyuv does use SIMD.
>>
>> Where? I didn't see any SIMD instructions in huffyuvenc.c or
>> huffyuvdec.c. Am I looking in the wrong place?
>
>It is not in huffyuvdec.c
>
>I will give more i
>You noted it wrong. Huffyuv does use SIMD.
Where? I didn't see any SIMD instructions in huffyuvenc.c or
huffyuvdec.c. Am I looking in the wrong place?
On Wednesday, October 16, 2013 4:45 PM, Paul B Mahol wrote:
On 10/16/13, James Board wrote:
>>And issue is probab
>And issue is probably withing avi container as it
>may not add every frame into index table.
>And when seeking you never check if returned packet actually is right
>one that you need.
>
>Or it could be bug in your code how you seek in file, etc...
I do check the results of the seek and I do check
fort can't possibly work. If
the answer is 'no, then I'll press on.
On Wednesday, October 16, 2013 12:56 PM, Carl Eugen Hoyos
wrote:
James Board writes:
> It would be nice if someone told me beforehand whether
> or not this is a problem that can be fixed.
>> I don't know that codec. I just knew it was lossless. So I guess
>> (unless there's a bug) the rule has an exception. Maybe the
>> 'adaptive tables' that google says it has adapt every 24 or so
>> frames. Don't have the source in front of me right now.
>>
>> But it's an FOSS project - anyon
>I have an libAV program that decodes every 24-th frame. This is for
>a video editor so I can easily seek forward in the video, rather than
>play all frames.
>If the input file is uncompressed AVI, then this works well.
>However, if I compress the video with ffvhuff or huffvuy, then whenever I
>s
with a file
container other
than AVI?
On Sunday, October 13, 2013 2:20 PM, Andy Shaules wrote:
On 10/12/2013 12:52 PM, James Board wrote:
In a C program with libav, how can I determine what is the largest
best_effort_timestamp
>for my input video file, which is AVI container and compresse
I have an libAV program that decodes every 24-th frame. This is for
a video editor so I can easily seek forward in the video, rather than
play all frames.
The high-level psuedo-code looks like this
for (int f = 0 ; f < LargeNumber; f+= 24) {
avformat_seek_file(ctx, 0, f, f, f, AVSEEK_
In a C program with libav, how can I determine what is the largest
best_effort_timestamp
for my input video file, which is AVI container and compressed with ffvhuff?
___
Libav-user mailing list
Libav-user@ffmpeg.org
http://ffmpeg.org/mailman/listinfo/lib
I have a C program that is using libav in a video editor. I want to decode
every 24th frame of the video (and nothing else). I wrote a loop which
uses avformat_seek_file() to seek to frame 0, then frame24, then frame 48,
then frame 72, etc. My input file is AVI container with the ffvhuff codec.
>This is a mailing list about FFmpeg (that is why
>it is hosted on the FFmpeg server). Questions
>about how to convert a C program (that allows
>implicit type conversions which is why FFmpeg
>- and demuxing.c - does not contain explicit
>type conversions) into a C++ program (which
>needs exp
program.
>Carl Eugen
On , James Board wrote:
>That's an example program written in C. There's nothing in the actual
codebase (as opposed to the >examples) that doesn't work in C++.
Yes, I know it's a program written in C. As I stated before, I only used that
So, if we can
figure out why demuxing.c won't compile with g++, then we will probably figure
out why my C++ app won't compile with g++.
On Tuesday, October 8, 2013 9:25 PM, Bruce Wheaton
wrote:
On Oct 8, 2013, at 11:12 AM, James Board wrote:
>
>I tried exactly that w
esn't
do what I want. I'll just choose another route.
On , Bruce Wheaton wrote:
On Oct 8, 2013, at 12:05 PM, James Board wrote:
I want to create several pthreads in a C++ program (assuming you can call
>libav routines from a C++ program) that each call libav subroutines.
&
I want to create several pthreads in a C++ program (assuming you can call
libav routines from a C++ program) that each call libav subroutines.
Are the libav subroutines thread-safe? Specifically,
can several pthreads open the same AVI file and decode different video
frames concurrently?
I'm d
>"How difficult would it be to compile the examples in the doc/examples
>directory with a C++ compiler?"
>
>Those are C programs, so just use a C compiler for them. That's all I
>meant.
Okay, I understand. Yes they are just C programs, so I can compile with
the C compiler. But my C++ programs
sholm wrote:
On 10/7/2013 5:31 PM, James Board wrote:
> I'm trying to incorporate the libav subroutines into a C++ program. Has this
> been
> done? When I try to compile, I get lots of errors like UINT64_c undefined and
> many others. How difficult would it be to compile
On Monday, October 7, 2013 5:39 PM, Michael Chisholm wrote:
On 10/7/2013 5:31 PM, James Board wrote:
> I'm trying to incorporate the libav subroutines into a C++ program. Has this
> been
> done? When I try to compile, I get lots of errors like UINT64_c undefined and
>
>But if you're compiling pure C code, why not use a C compiler?
I'm not compiling pure C code. I'm compiling C++ code and I want
to call the libav surboutines from C++ code. How do I do this?___
Libav-user mailing list
Libav-user@ffmpeg.org
http://ffm
I'm trying to incorporate the libav subroutines into a C++ program. Has this
been
done? When I try to compile, I get lots of errors like UINT64_c undefined and
many others. How difficult would it be to compile the examples in the
doc/examples
directory with a C++ compiler?
In the libAV examples distributed with ffmpeg, I see the following code:
// Flush cache frames
do {
decode_packet(&got_frame, 1);
} while (got_frame);
What are cached frames and what does the above do? Is this explained
anywhere?
In my libav app, I'm trying to do simple edit
>>Okay, that's helpful. But then how and where and by what program is
>>timebase calculated? Do the ffmpeg tools calculate it? I don't see
>>how they can. They'd have to look at every frame in the video and
>>that could take a very long time.
>
>You should know that video formats reserve some
>Timebase simply defines the maximum granularity of your timestamps. If
>for some reason (e.g. to synchronize frames with content from other
>tracks in the same file) there can be cases where it needs to be finer
>than 1/frame rate. If you just learn how to calculate with it (see the
>formula in m
>> Anyway, it sounds like pts and best_effort_timestamp are really frame
>> numbers
>
>No, they are not. It is the case if timebase = 1/framerate but that is
>not guaranteed at all and should be seen as a special case, unless for
>some reason you know all your files are that way (and they typicall
>> Yes, I looked at avcodec.h and could not find what I wanted. When I was
>
>You wrote:
>
> pts
> pkt_pts
> pkt_dts
> coded_picture_number
> display_picture_number
> best_effort_timestamp (the name of this one really worries me)
> pkt_pos
> pkt_duration
>What do those all
>Try looking at the documentation in the header files, in this case
>avcodec.h. It should help you quite a bit.
Yes, I looked at avcodec.h and could not find what I wanted. When I was
previously discussing the inaccuracy of floating-point numbers and how I wanted
to use frame numbers in editing,
>How to seek is actually quite easy so I won't explain that (google it and you
>find it easily), but keep in mind that you must seek to key frames. How to
>(fast) seek to any frame is something I haven't figured out myself, it's not
>something ffmpeg seems to support so I fear you'd have to seek t
I'm writing a libAV application in C, and I'm trying to use the
av_seek_frame() or avformatseek_file() to move within the video stream.
Ideally, I'd like to seek to frame number N. I'd like a subroutine that seeks
to frame number N, but I think from previous discussions, that isn't the way
things
>> However, what if I only copy a subset of the input frames to the output
>> file? Can I still copy the packet? If the answer is no, can I do something
>> simple to allow me to copy the packet (like modify a timestamp?).
>
>The best advice again would be to try and see if there is some
>problem
In the libAV examples distributed with ffmpeg, I see the following code:
// Flush cache frames
do {
decode_packet(&got_frame, 1);
} while (got_frame);
What are cached frames and what does the above do? Is tis explained
anywhere?
In my libav app, I'm trying to do simple edit
>> In between the two calls above, I have to convert the image data from
>> myFrameDecode to image data in myFrameEncode. That's what I'm having
>> trouble
>> with. Right now I have lots of row/col loops and they do things differently
>> for different pixel formats. Is there a single subroutin
>Generally speaking, the answer is yes, you can simply copy encoded
>packets from demuxer to muxer, if you don't change them. I am sure AVI
>container will not be upset, but out in the wild, there could be some
>containers for which this trick may be less straightforward to
>implement.
>
>General
>> Also, if the input and output file have the same pixel format, is there a
>> simple way to copy the data from one to the other?
>>
>> Thanks
>You don't need to copy data between frames, you can reuse the decoder frame as
>input for encoder.
Okay. I will try this (actually, I tried it and it
I'm writing a simple libAV program that reads an AVI file, decodes each
frame, then writes that frame data to another AVI file as output. The output
file should be pretty much the same as the input file.
I'm using the examples in the ffmpeg source as a start. This is how
each frame from the inpu
>> Also, and this probably isn't a libav question, but how can I tell
>> if my input AVI file is vfr or cfr?
>
>By looking at frame timestamps.
I tried this:
ffmprobe IN.avi -show_frames | grep pkt_pts_time
Is that the correct way to look t time stamps? Are those the real
timestamps, or ar
Let's say I have an input video (AVI format) that is vfr, and I write
a libav application that steps through each frame in the video and
does something: maybe I write that frame to a file on disk. Will
I have vfr-problems where the libav is duplicating frames, or removing
frames (behind the scenes
>
>When using libs you are on your own. The VFR/CFR comes with ffmpeg tool.
So it sounds like what yo're saying is that with the libs, I won't have the
same issues with the ffmpeg feature where it duplicated input frames in
order to meet some unspecified constant frame rate? With the libs, when
Is there a way to use libav to encode and decode a single frame of
image data with a lossless codec such as ffvhuff? I know this can
be done with video. But if I have a single frame of image data stored
in a ppm or pnm file, can I read it into my libAV program, compress with
the ffvhuff codec, an
>>On 9/5/13, James Board wrote:
>> Is there a way to use libav to encode and decode a single frame of
>> image data with a lossless codec such as ffvhuff? I know this can
>> be done with video. But if I have a single frame of image data stored
>> in a ppm or p
From: Thomas
To: "This list is about using libavcodec, libavformat, libavutil, libavdevice
and libavfilter."
Sent: Thursday, July 18, 2013 8:55 AM
Subject: Re: [Libav-user] How to decode arbitrary frame
>You can use avformat_seek_file() followed by avco
I have the doc/examples programs compiled and running. I use
the program demuxing.c to decode an AVI file. From the source
code, it looks it calls its own subroutine decode_packet() to decode
the next video or audio packet, and that subroutine calls
avcodec_ecode_video2()to decode the next fram
>I don't know how to fix that. Do you know what I must do to get
>the examples in doc/examples in the ffmpeg source code to compile?
Never mind. I did the following and then the examples compiled:
setenv PKG_CONFIG_PATH /usr/local/lib/pkgconfig
_
>You need updated headers and pkg-config installed in your system. Also
>read the README file for further instructions.
I did a 'make install' of ffmpeg, and after that, I tried
to build the libavcodec examples in doc/examples. I received lots of
'undefined reference' errors after running 'make'
>On date Tuesday 2013-07-16 09:11:53 -0700, James Board encoded:
>> I'd like to write a C or C++ program which uses libavcodec to retrieve
>> individual frames of an AVI file. I can't find much documentation on
>> the WWW. But there are examples in the ffmpeg sour
I'd like to write a C or C++ program which uses libavcodec to retrieve
individual frames of an AVI file. I can't find much documentation on
the WWW. But there are examples in the ffmpeg source distribution. I tried
to compile them, but that failed because there is no file: channel_layout.h.
Any
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