[gst-devel] AMR caps incompatibility between muxer and encoder

[Benoit Fouet]

Deeptendu Bikash wrote:
> Hi Ben,
>  
> Can you tell me how you did it? I am trying to mux AMR audio into a
> mov file, but all I get in output is a 182 byte file. I used the pipeline
> filesrc ! audio/AMR,rate=8000,channels=2 ! ffmux_mov ! filesink.
if your source file is an amr file, you have to parse it and mux it, and
that should be all...
something like: filesrc ! amrnbparse ! ffmux_3gp ! filesink
(don't know if this one works though, 'cause i cannot test it here...)
one thing too: AMR is always mono so using 2 channels is useless...
> (I checked that the file does indeed have a #!AMR header).
output file will not have such a header. if your input file has one, i
guess amrnb parser element will just skip it, although i didn't really
got into the parser...
parsing the input file and giving it to the muxer should produce a
correct 3gp file :)

-- Ben
>  
> I even tried doing it in mp4 using a AAC file as input and ffmux_mp4.
> When I tried to run the output file, the players show the duration as
> more than 8000 hours and are not able to play it at all! I am totally
> at a loss.
>  
> Would really appreciate some help here.
>  
> Deeptendu
>
>  
> On 10/25/06, *Benoit Fouet* <benoit.fouet at purplelabs.com
> <mailto:benoit.fouet at purplelabs.com>> wrote:
> that does :)
> indeed, I modified a bit the amrnb- dec/enc stuff a bit here, so that it
> handles the amr header.
> (to avoid the use of the amr parser)
> sorry for all the noise, it seems i told a lot of stupid things
> yesterday...
>
> indeed, thanks for explanation Daniel !
>
>     Daniel Díaz wrote:
>     > Hello there!
>     >
>     >
>     > On 10/25/06, Benoit Fouet < benoit.fouet at purplelabs.com
>     <mailto:benoit.fouet at purplelabs.com>> wrote:
>     >
>     >> Hi
>     >>
>     >> SP GLE wrote:
>     >>
>     >>> Hi,
>     >>> I'm trying to link an 'amrnbenc' element and a 'ffmux_mov',
>     >>> amrnbenc SRC caps are
>     >>>    Capabilities:
>     >>>       audio/AMR
>     >>>                    rate: 8000
>     >>>                channels: 1
>     >>>
>     >>> ffmux_mov SINK Caps are
>     >>>       audio/x-amr-nb
>     >>>                    rate: [ 8000, 96000 ]
>     >>>                channels: [ 1, 2 ]
>     >>>
>     >>> so linking seems incompatible, how can i link these elements ?
>     Is there
>     >>> a way to change capabilities ?
>     >>>
>     >>> failed negotiation between pads is attached for the following
>     cmd :
>     >>> GST_DEBUG=4 GST_DEBUG_NO_COLOR=1  gst-launch audiotestsrc !
>     >>> audioconvert ! amrnbenc ! ffmux_mov ! filesink
>     location=/tmp/f.mov
>     >>>
>     >>> Thanks.
>     >>>
>     >>>
>     >> you have to change the source code of amr decoder, so that it is
>     >> audio/x-amr-nb too on its sink pad.
>     >>
>     >
>     > Why was that, again?
>     >
>     > As I understand it, audio/x-amr-nb-sh is "MIME-ful" AMR narrow band,
>     > that is, with a header like this: `echo '#!AMR' > header.amr`.
>     >
>     > Then, audio/AMR is "MIME-less" AMR information. Certainly, the
>     output
>     > of the amrnbenc is lacking such header because it is pure AMR
>     data, no
>     > MIME header.
>     >
>     > That's why amrnbparse takes audio/x-amr-nb-sh and outputs audio/AMR.
>     >
>     > See section 8.1 of RFC 3267, where it says that MIME type for
>     AMR is
>     > precisely audio/AMR, with audio/AMR-WB being used for wide band.
>     >
>     > Also, I vaguely recall that one of the de/muxers needed such header
>     > for AMR, or needed it not when coming from RTP. Or something
>     > in-between :) But in any case, it is possible to have a complete
>     > pipeline with those elements without changing the source code.
>     >
>     > Hope that makes some sense.
>     >
>     that does :)
>     indeed, I modified a bit the amrnb- dec/enc stuff a bit here, so
>     that it
>     handles the amr header.
>     (to avoid the use of the amr parser)
>     sorry for all the noise, it seems i told a lot of stupid things
>     yesterday...
>
>     indeed, thanks for explanation Daniel !
>
>     -- Ben
>
>     > Daniel Díaz
>     > ddiaz at ti.com <mailto:ddiaz at ti.com>
>     >
>     >
>     >
>
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