Hi Elen,
libmpeg2's job doesn't really extend to the display of the decoded
sequences beyond the simple example code you saw. In a full MPEG-2 video
decode-and-display application, you would need to display the decoded
fields or frames at intervals separated by the field period or frame
period
On Thu, 12 Oct 2006, Balaji Raman wrote:
> I want to count the number of bits for each macroblock after VLD and IQ
> task execution, also I want to count the number of bits for each
> macroblock after IDCT and MC execution. Can you advice me how to do
> this?
Hi Balaji,
Sounds fun! You should
Hi Anand,
Not sure exactly what you mean. Are you asking about:
(1) The number of bits required to code each picture (e.g., "911376 bits
for the I frame, 115936 for the B frame after it, etc.")? For this, you'll
have to call mpeg2_getpos() to get the position in the stream as you hit
PICTURE h
anyways i am really glad for ur quick reply.
>> If i get any more doubts..i will try to
>> mail you.
>>
>> Thanks & regards
>>
>> Anand.
>>
>>
>>
>>
>> On 4/4/07, Keith Winstein <[EMAIL PROTECTE
i take the difference of
> mpeg2_getpos() return values when it hits the STATE_PICTURE(when the picture
> header is found) and STATE_SLICE(when the last slice of a picture has been
> found) to get the exact frame size.
> Thanks in advan
Hi Sebastian,
Unfortunately, MPEG-2 isn't quite this simple. The approach you're
describing will only work on a *closed* GOP. In normal (non-closed) GOPs,
decoding the first two B frames will require access to the previous P
frame -- from the previous GOP.
Here's an example of what you'll see
ore if
> required.
>
> so i need calrification whether what i
> am doing is correct or not..
> I can use the secondary method u suggested but i am using,libmpeg2 already
> for getting the other info like chroam_width etc..
>
>
Hi Keith,
>
> Thanks for this example. In this example, would the first picture that is
> displayed
> be the P-picture in the second GOP followed by the I picture? I am getting a
> little
> confused about the display order of the all the frames.
>
> Thanks
> Dinkar
&g
me, decode it (it stands alone) and display the
*previously encountered* "reference frame" if one exists.
(4) If you hit a P-frame, decode it (using the previous "reference frame")
and display the previously encountered "reference frame" if one exists.
-K
Hello,
Can you please post a section of this file on the Internet so we can
examine it? Maybe you've got a transport stream instead of an elementary
stream or something like that.
-Keith
On Wed, 25 Apr 2007, hdzhang wrote:
> hi, now I receive mpeg2 data from satelite receiver.
> But when I ru
Allison,
I have no idea. Please post the file somewhere or we won't be able to help
you.
-Keith
On Wed, 25 Apr 2007, hdzhang wrote:
Keith,
I used a "MPEG push demultiplexer".
Is data from this demultiplexer TS or ES?
Allison
??2007-04-25??"Keith Winstei
if (info->discard_fbuf)
((struct fbuf_s *)info->discard_fbuf->id)->used = 0;
break;
default:
break;
}//end switch
} while (bMem!=2);
return S_OK;
}
??2007-04-25??"Keith Win
Yugandhar,
libmpeg2 only decodes MPEG-2 part 2 (video). It doesn't have anything to
do with MPEG audio. And it only does the decoding process, not the output
process (which would include synchronization with other streams, like
audio, and timing).
If you want an integrated decoder, try vlc (ww
Allison,
I don't understand exactly what you mean by "SD DV mpeg2 data". DV (aka,
MiniDV) is a different format that does not use MPEG-2.
Assuming you're just referring to interlaced content, there is no perfect
way to display interlaced material on a progressive display like a
computer moni
Allison,
On Wed, 9 May 2007, hdzhne wrote:
Is "info->display_fbuf->buf" one field or one frame data (my mpeg2
source is interlaced)?
I think it's always a frame. (Not 100% sure in the case of field pictures,
but nobody seems to use those. I think it's still a frame even when field
pictures
Allison,
You're a bit confused on the terminology.
MPEG-2 can use FRAME PICTURES or FIELD PICTURES.
If it uses frame pictures, they can be INTERLACED or PROGRESSIVE.
Much ATSC HDTV content is sent as interlaced frame pictures. The resulting
frame you get from libmpeg2 has the odd field on the
On Mon, 14 May 2007, hdzhne wrote:
> So, does info->diaplay_fbuf->buf in libmpeg2 store odd filed followed by
> even field if HDTV content is sent as interlaced frame picture? Just I
> need reorder two fields to one full frame which can be displayed
> directly?
buf[] is an array of three fram
Johann,
You can have ffmpeg decode a stream. On Linux, for example, just have it
read from /dev/stdin and pipe the stream to it.
Regards,
Keith
On Sun, 19 Aug 2007, Johann Horvat wrote:
> Dear libmpeg2 people,
>
> I know that libmpeg2 is not able to decode MPEG4 streams, but can please tell
>
Hi Krishna,
Sorry, I don't understand your question. Are you talking about the
computation time required to decode the headers, or literally the decoding
time (aka, when must a particular MPEG-2 picture be decoded)? I guess the
real question is, what are you trying to do? I think if you gave us
Is
> that a fixed time for all the frames or pictures...if it is so, what is the
> general time or how do i get to know in the libmpeg2 [mpeg2dec 0.4.1].
>
> I am trying to find the decoding time for a GOP using the mpeg2dec.c
>
> Cheers
> Krishna Prasad
>
> On Fri,
;
> Cheers
> Krishna Prasad
>
> On Fri, Feb 15, 2008 at 2:23 AM, Keith Winstein <[EMAIL PROTECTED]> wrote:
>
>> Hi Krishna,
>>
>> Thanks for clarifying. Better not to call that the "decoding time," which
>> is a specific defined term in the MPEG-2
Hi Krishna,
That sounds plausible. Make sure you're running mpeg2dec with "-o null" so
that none of your time is consumed with drawing (aka displaying) the
frame.
It's hard to know for sure without seeing the code, but if the output is
plausible and if adding up all the individual times is clo
Hi Krishna,
There's no exact formula -- it's very hard to exactly quantify the
performance of a general-purpose computer.
In general, the bigger the frame (in resolution), the more work it'll take
to decode.
The bigger the frame (in number of bits used to code it), the longer it'll
take to decod
Hi Krishna,
I did some experiments on a Pentium 4 at 3 GHz with libmpeg2 0.4.1, using
some MPEG-2 video streams I had lying around of various resolutions. Here
are the results:
Luminance resolution -- speed
720x480 -- 319 fps
1280x720 -- 124 fps
est,
Keith
On Fri, 29 Feb 2008, Krishna Prasad wrote:
> Hi Keith
>
> Thanks for your earliest reply.
> I will look in to the details of whatever you had sent.If I have any doubts,
> I will keep you posted.
>
> Regards
> Krishna Prasad
>
>
> On Fri, Feb 29, 2008 a
Hi Mateus,
You're right that the literal output of the inverse DCT is saturated to
the range [-256 .. 255]. MPEG-2 pt. 2 calls this the "transform data,"
f[y][x]. See clause 7.5.
Meanwhile, the motion vectors are applied to other pictures to produce
blocks of "prediction samples," p[y][x].
Th
On Thu, 1 May 2008, Thomas Richards wrote:
> I'm attempting to write a small application that extracts the durations
> from MPEG2 files. I've been looking at the documentation and the
> samples, and have come up with a simple app that calls "mpeg2_parse()"
> until it returns "STATE_GOP", and when
On Fri, 2 May 2008, Thomas Richards wrote:
> I now have a first-pass solution working. Basically I iterate over the
> entire file, and count the number of times I get STATE_PICTURE from the
> mpeg2_parse function.
>
> This works, but it's horribly slow. A 24 minute clip (400 MB on disk)
> takes
Hi Craig,
On #1, I think we're good -- you can only have one sequence_extension
following a sequence_header. See 13818-2, clause 6.3.1
("sequence_extension() shall only occur immediately following a
sequence_header()").
On #2, I think that's a real bug (that would, as you point out, only
affe
Hi Hibiki,
We can help walk you through this, and I'm happy to help you with some
demo code if you'd like. I don't know of any existing program that meets
your needs.
It might help if you explained what the overarching goal is.
The problem is that MPEG-2 may be more interdependent than you rea
Hi Gus,
libmpeg2 itself can only parse an MPEG video elementary stream -- video
only.
Within the MPEG-2 world, a stream that combines video and audio is an
MPEG-2 systems stream -- either a transport stream or a program stream.
You can demultiplex these with the mpeg2dec and extract_mpeg2 ex
Hi Gus,
If I had to make a wild guess, you're trying to play an MPEG-2 system
stream (a transport stream or program stream).
sample2.c only works on an MPEG-2 video elementary stream -- the raw video
that is multiplexed into the system stream.
Does the file play back properly with mplayer o
Hi Gus,
FFmpeg's libavcodec can also decode MPEG-2 video and is licensed under the
LGPL.
Best,
Keith
On Thu, 16 Jul 2009, Gus Issa wrote:
Hello,
Is there a library out there that is similar to libmpeg2 but available
for commercial licensing (not GPL)? Or can libmpeg2 be licensed non-GPL?
Hello İşbaran,
If you feed libmpeg2 bad data (e.g., if you're dropping packets and not
replacing them), you will certainly see green blotches -- that's generally
what you see when there's missing intraframe data.
(There are more sophisticated ways of doing error concealment in the
presence o
you actually want usable video, you need some
of the practical improvements above...
Happy hunting,
Keith
On Tue, 22 Sep 2009, İşbaran Akçayır wrote:
2009/9/8 Keith Winstein
Hello İşbaran,
Helloes again,
If you feed libmpeg2 bad data (e.g., if you're dropping
packets and
Andrey,
Please post foo.mpg somewhere we can get to it as well, please. We need
that to see if it's a valid MPEG-2 video elementary stream. Just the first
10 megabytes is enough.
Just to emphasize: libmpeg2 decodes MPEG-2 video elementary streams
(streams that can contain video only). If the s
Hi Matthew,
We're here. Unfortunately I don't have Windows and would have a hard time
trying to reproduce this problem for you. (It works fine for me with gcc
on Linux; I recognize that's not very helpful to know.)
Are you able to compile the "mpeg2dec" program that ships with libmpeg2?
Does i
Daniel,
It's hard to help you debug this without knowing what you are feeding
in. To be clear -- you are using a valid MPEG-2 video elementary
stream that plays perfectly fine with mpeg2dec and the other sample
decoders distributed with libmpeg2? Maybe if you can post a sample of
your file, I can
Hi pebble,
I'm not sure exactly where you're getting the [0, 32768] (the DC
component can be negative), but I think you may probably barking up
the wrong tree. IEEE 1180 only defines the IDCT statistically, so
different MPEG-2 decoders can produce slightly different output.
libmpeg2 may even produ
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