playback of mpeg-4 anamorphic content on Windoze

[Mike]

Hi,
I have a problem playing digital TV recordings in MS-windows after
mpeg4/divx compression.
While players (e.g. WinMP, Real) show the correct 16:9 aspect ratio
for mpeg-2 encoding, they ignore the same information in mpeg-4 files,
and assume the 720x576 pixels are square.
Is this a common bug in windows players, or is it a problem with
my codecs? Any suggestions for a player or codec that will handle
it correctly?

What do other people do?
Should I convert the AVI to 1024x576 so pixels are square. If so,
will I need a higher bitrate to preserve quality?

I'm using mencoder under Linux, with "autoaspect" to recompess the videos.

[RJ]

Some players are smart enough to play anamorphic AVIs in the correct aspect
ratio :-

Zoomplayer (Standard version is free)
http://www.inmatrix.com/files/zoomplayer_download.shtml

Creative PlayCenter (comes free with Creative Labs sound cards)

There may be others.
---------------------------------------------------------------------

Mike <nospam.really@westnet.com.au> wrote in message
news:40d9331c$1@quokka.wn.com.au...
> Hi,
> I have a problem playing digital TV recordings in MS-windows after
> mpeg4/divx compression.
> While players (e.g. WinMP, Real) show the correct 16:9 aspect ratio
> for mpeg-2 encoding, they ignore the same information in mpeg-4 files,
> and assume the 720x576 pixels are square.
> Is this a common bug in windows players, or is it a problem with
> my codecs? Any suggestions for a player or codec that will handle
> it correctly?
>
> What do other people do?
> Should I convert the AVI to 1024x576 so pixels are square. If so,
> will I need a higher bitrate to preserve quality?
>
> I'm using mencoder under Linux, with "autoaspect" to recompess the videos.

[Mike]

RJ wrote:
> Some players are smart enough to play anamorphic AVIs in the correct aspect
> ratio :-
>
> Zoomplayer (Standard version is free)
> http://www.inmatrix.com/files/zoomplayer_download.shtml

Thanks, but that has the same problem. It recognises the aspect ratio
for mpeg2 (as broadcast), but not after conversion to mpeg-4/divx .
Have you actually used it to display anamorphic mpeg4 videos??

Could it be the codec? What codec do you use?

>>Hi,
>>I have a problem playing digital TV recordings in MS-windows after
>>mpeg4/divx compression.
>> While players (e.g. WinMP, Real) show the correct 16:9 aspect ratio
>>for mpeg-2 encoding, they ignore the same information in mpeg-4 files,
>>and assume the 720x576 pixels are square.
>> Is this a common bug in windows players, or is it a problem with
>>my codecs? Any suggestions for a player or codec that will handle
>>it correctly?
>>
>>What do other people do?
>>Should I convert the AVI to 1024x576 so pixels are square. If so,
>>will I need a higher bitrate to preserve quality?
>>
>>I'm using mencoder under Linux, with "autoaspect" to recompess the videos.
>
>
>

[andw]

Bsplayer http://www.bsplayer.org/ allows you to cycle through different aspect ratios by hitting the 'A' key on the keyboard (4:3, 16:9, original and anamorphic)

[Matt McLeod]

In article <40d9331c$1@quokka.wn.com.au>,
Mike <nospam.really@westnet.com.au> wrote:
> Is this a common bug in windows players, or is it a problem with
>my codecs? Any suggestions for a player or codec that will handle
>it correctly?

mplayer is the only thing that pays any attention to the aspect
ratio stuff in the AVIs mencoder creates.

Generally I resize during the encode, typically to 480x270 for 16:9
content, 480x360 for 4:3 (with appropriate cropping before the resize
in the latter case). Make sure you tell it to use a decent software
scaler and the results are usually pretty reasonable.

Matt

[RJ]

> but that has the same problem.

It's not automatic, you have to set an option for what aspect ratio you want
it to display.

----------------------------------------------------------
Mike <nospam.really@westnet.com.au> wrote in message
news:40da3e6f@quokka.wn.com.au...
> RJ wrote:
> > Some players are smart enough to play anamorphic AVIs in the correct
aspect
> > ratio :-
> >
> > Zoomplayer (Standard version is free)
> > http://www.inmatrix.com/files/zoomplayer_download.shtml
>
> Thanks, but that has the same problem. It recognises the aspect ratio
> for mpeg2 (as broadcast), but not after conversion to mpeg-4/divx .
> Have you actually used it to display anamorphic mpeg4 videos??
>
> Could it be the codec? What codec do you use?
>
> >>Hi,
> >>I have a problem playing digital TV recordings in MS-windows after
> >>mpeg4/divx compression.
> >> While players (e.g. WinMP, Real) show the correct 16:9 aspect ratio
> >>for mpeg-2 encoding, they ignore the same information in mpeg-4 files,
> >>and assume the 720x576 pixels are square.
> >> Is this a common bug in windows players, or is it a problem with
> >>my codecs? Any suggestions for a player or codec that will handle
> >>it correctly?
> >>
> >>What do other people do?
> >>Should I convert the AVI to 1024x576 so pixels are square. If so,
> >>will I need a higher bitrate to preserve quality?
> >>
> >>I'm using mencoder under Linux, with "autoaspect" to recompess the
videos.
> >
> >
> >

[Mike]

RJ wrote:
>>but that has the same problem.
>
> It's not automatic, you have to set an option for what aspect ratio you want
> it to display.

OK, thanks!
Thats still a big improvement on other Windows players.

[Mike]

Matt McLeod wrote:

> mplayer is the only thing that pays any attention to the aspect
> ratio stuff in the AVIs mencoder creates.

A pity, since its supposed to be in the standard, and there are no
alternatives with the AVI file.

> Generally I resize during the encode, typically to 480x270 for 16:9
> content, 480x360 for 4:3 (with appropriate cropping before the resize

It seems a shame to scale it down so much, especially with a nice
digital source. Maybe I'll try 720x405 for 16:9.

> in the latter case). Make sure you tell it to use a decent software
> scaler and the results are usually pretty reasonable.

Do you consider the mplayer/mencoder scaler decent?

[Matt McLeod]

In article <40db7b1c$1@quokka.wn.com.au>,
Mike <nospam.really@westnet.com.au> wrote:
>Matt McLeod wrote:
>> mplayer is the only thing that pays any attention to the aspect
>> ratio stuff in the AVIs mencoder creates.
>
>A pity, since its supposed to be in the standard, and there are no
>alternatives with the AVI file.

I haven't read the standard, and am merely going by what the mplayer
documentation has to say about it.

>> Generally I resize during the encode, typically to 480x270 for 16:9
>> content, 480x360 for 4:3 (with appropriate cropping before the resize
>
>It seems a shame to scale it down so much, especially with a nice
>digital source. Maybe I'll try 720x405 for 16:9.

There's a tradeoff: the bigger the picture, the higher the bitrate you
need to maintain a decent image quality.

I generally encode the video at 800kbps, which is a little higher than
some people use, but still produces reasonably small files. I've found
that the resulting files play back quite nicely when displayed on my
76cm widescreen TV.

I have played around a bit with larger picture sizes, but couldn't really
tell the difference. So I figure it's better to have a bit more overhead
for high-motion scenes than to have the bigger image.

Movies are a different case altogether. In that case you're typically
trying to make it fit in 700MB, so the video bitrate will depend on the
length of the thing, and if you can get a higher bitrate then you can
quite reasonably increase the image size.

>> in the latter case). Make sure you tell it to use a decent software
>> scaler and the results are usually pretty reasonable.
>
>Do you consider the mplayer/mencoder scaler decent?

I typically use "-sws 2". mplayer has a bunch of software scalers.
I haven't really evaluated them seriously, just found that 2 seemed
pretty reasonable.

I think it chooses an OK one by default anyway. I've never really noticed
any huge problems, at least not on the scale you get when resizing with
VirtualDubMod on Windows if you forget to change from the default
"nearest neighbour" algorithm, anyway.

But really it's all pretty subjective. Use whatever combination suits
you, just remember that the aspect ratio stuff is generally ignored so
you may as well resize.

Matt