[streaming] Re: Streaming mp4+AAC to mobile phones

Tue Dec 13 20:35:15 CET 2005

Hai,

I only saw this postings now: Here are my test results and findings:

I encode a satellite signal into mp4 (vcodec=mp4v acodec=mp4a) this is
served via VLC via HTTP to the second server that has vlc and darwin on it
(I need to use VLC to transport the stream via the network since DSS
injection doesn't work. The 2nd VLC receives the stream and serveses it to
DSS and creates the .sdp file. The stream is visible with QuickTime on PC
and Mac but not with Real. The stream doesn't play on my UMTS phone
(SonyEricsson Z1010). 

And now for the *strange* part....
When I kill the audio or use acodec=samr VLC says it cannot find the codec
and streams out video only. This stream IS visible on my mobile.

If I take a look at the created .sdp file it say audio format *mpeg4
generic* but this should be *mpeg4 latm* (according to DSS)

Turns out either the mobile phone OR DSS wants the audio encoded in AAC HE -
LATM 

I haven't been successfull in compiling VLC/FFMpeg with amr to test that....

I fear the only way to solve this is a correct implementation of AAC HE
-LATM by or in VLC (but I'm not a programmer).

Has anyone ever tried to use VLC directly with a mobile or any other media
server for that matter? (catraserver i.e.)

Steit!

-----Oorspronkelijk bericht-----
Van: streaming-bounce at videolan.org [mailto:streaming-bounce at videolan.org]
Namens PERET Pierre-Hugues
Verzonden: dinsdag 13 december 2005 17:10
Aan: streaming at videolan.org
Onderwerp: [streaming] Re: Streaming mp4+AAC to mobile phones

I give up !
it's time to pass to another thing... i cannot afford spending more time on
that .
If anyone find the solution , let me know.

At 16:36 13/12/2005 +0100, you wrote:

...because the mobile tries to load the stream (instead of telling you that
this type of stream is not supported), right? So maybe it is an sdp issue...
One thing to test if aac is supported at all might be:
1) encode a video with mp4/aac using vlc
2) hint the encoded file with mp4box and put it in DSS' streaming dir
3) access the encoded file directly without using an sdp file (e.g.
rtsp://server:port/myfile.mp4) to see if aac sound works.
==> If it does not work, i bet it's the phone not soppurting aac. Then we
are sure that there's nothing wrong with the sdp (because it's not involved
here) and it's also not the fault of VLC's mp4a packetizer (because this one
is not involved when VLC encodes to file)
==> On the other hand, if it works, then there must be something wrong with
either the sdp or the packetize_mp4a method -- or something completely
different :-/

I encoded a mp4/aac file, and hinted it with mp4creator , and sound is not
working. For this one, i think its a DSS issue, because the
sample_100kbit.mp4 (with aac) doesn't work either with DSS.
I'm trying to find a streaming server that can stream mp4/aac to mobile
phones.

when playing with the sdp file,i can make my mobile phone loading my aac
stream, but not playing it (player stuck at the end of loading).

Unfortunately I can't test the stream right now, because my current provider
does not allow any other traffic than http :(

looking at the code of the rtp module, i noticed amr / mpa4 sections seems
inappropriate for mobile streaming (looks normal). unfortunatly i'm not able
to implement such thing. Maybe i'm completely wrong ...
correct me in this case.

At 17:48 12/12/2005 +0100, you wrote:

Well,
back again !
streaming amr_wb is the same as amr_nb.. it doesn't play in QTplayer because
it doesn't have the codecs, but the mobile player seems to accept it, but no
sound is coming.
switch back to amr_nb and play with the sdp file....

At 11:55 12/12/2005 +0100, you wrote:

I came to the same conclusion as you .
For now, i'm working on the sdp stuff which i think is the problem. Or it
might be the reflector module of DSS (in this case i doubt i could do
anything for it).

At 17:02 11/12/2005 -0800, Torben Knerr wrote:

On 12/11/05, PERET Pierre-Hugues <ph.peret at free.fr> wrote:

Didn't tried with ffmpeg's amr_wb.
trying with http allways make my operator says wrong url, putting the full
path or not.

I talked on irc with some guys, and it seems that it's not very possible to
do what i want , and someone oriented me to helix mobile server and mobile
encoder, but it's far too expensive....

as i want to take an already running stream and transcode it to 3gp , i
think i cannot do that with opensource or free software. 

I think it is possible with vlc+dss, as soon as the sound issue is solved.
Even though the stream might not be 100% 3gp spec compliant, it worked (at
least with video only). 

I noticed that DSS is not able to stream mp4+aac to mobile phone -> nokia
6630 , sound is not working, even with the sample which comes with the
server. Making aac streaming working on the mobile would be the
solution.(amr is not my preference).

I think that's not possible with the 6630, because it can not play aac
streams :( 
On the other hand DSS _is able_ to stream mp4+aac (as you can see the stream
with different players, such as QT), so imho it is definitely the mobile,
which is _not able_ to play rtsp-streamed aac.
But you are right, amr_nb is no solution because it is too crappy... amr_wb
might be okay, even though not as good as aac.

if you know a streaming server that can do that.. pls tell me.
maybe tomorrow i will try amr_wb . i will keep you informed.

NB : 3gp or mp4 generated by vlc doesn't play on the mobile phone on local
playback (possibly beacause of the lack of hinted tracks)

Right, for local playback you need to hint the files. I used mp4box for
hinting and got it work to play locally with mp4+aac and mp4+amr (both
encoded with vlc). Don't remember if it worked with h263 video too, but i
guess so.

Good luck with the amr_wb stuff!

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