Mailinglist Archive: opensuse (2803 mails)

[David Bolt <bcrafhfr@xxxxxxxxxx>]

On Tue, 22 Jul 2008, Rodney Baker wrote:-

> On Sun, 13 Jul 2008 04:11:50 David Bolt wrote:

<Snip>

> > # get a temporary filename
> > #
> > TEMPFILE=$(mktemp)
> >
> > # and then use it to create named pipe
> > #
> > rm "${TEMPFILE}"
> > mkfifo "${TEMPFILE}"

<Snip>

> > ffmpeg -f rm -i "${TEMPFILE}" -f mp3 -ab 160k "${OUTPUT}" </dev/null &

<Snip>

> Thanks, David. ffmpeg doesn't actually need the -f parameter to set the output
> format - it will auto-detect from the output file extension (which means that
> the script can automatically handle video as well as audio-only streams).

That only works when ffmpeg recognizes the extension. However, since the
temporary pipe doesn't have an extension it will recognize[0], you need
to specify the format.

> That being said, I might play with adding a couple of optional command line
> parameters to specify output format details if needed. That could make it
> easy to download  and convert to pal dvd format in one step :-).

That's easy:

ffmpeg -i "<input filename>" -target pal-dvd -y "<output filename>"

or

ffmpeg -i "<input filename>" -target pal-dvd -acodec mp2 -y "<output filename>"

depending on what you want the audio stream type to be. The default is
to use an AC3 audio stream, which supports 5 and 7 audio channels, as
opposed to mp2 which only supports stereo[1].

In both cases, the input streams are transcoded to an MPEG2 stream with
the audio stream is up-sampled to 48KHz if required. Also, if required,
the video is transcoded with a 25fps frame-rate and/or re-sized to
720x576.

The same is true for making NTSC compatible MPEG2 streams, where you'd
use either:

ffmpeg -i "<input filename>" -target ntsc-dvd -y "<output filename>"

or

ffmpeg -i "<input filename>" -target ntsc-dvd -acodec mp2 -y "<output filename>"

In this case, if it's required, the video is transcoded with a 29.97fps
frame-rate and/or re-sized to 720x480.


[0] It's created in the format /tmp/tmp.xxxxxxxxxx where the
'xxxxxxxxxx' is made up of the process ID and random alphanumeric
characters

[1] it also supports mono, but you won't be using that with a stream to
be used on a DVD.

Regards,
        David Bolt

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