[libav-tools] capture and stream to rtmp from a single source?

Luca Barbato lu_zero at gentoo.org
Sun Dec 15 04:11:51 CET 2013


On 13/12/13 19:49, Jeremy Hansen wrote:
> 
> On Dec 13, 2013, at 5:25 AM, Luca Barbato <lu_zero at gentoo.org> wrote:
> 
>> On 12/12/13 05:10, Jeremy Hansen wrote:
>>>
>>>
>>> On Dec 11, 2013, at 5:32 AM, Luca Barbato <lu_zero at gentoo.org> wrote:
>>>
>>>> On 11/12/13 03:41, Jeremy Hansen wrote:
>>>>>
>>>>> Right now I’m using avconv to capture video from a BlackMagic Design Mini Recorder PCIe card.  This is working great.  My next step is to trying to stream live to a rtmp server (Using nginx and the rtmp module).  
>>>>>
>>>>> Here’s my current command line:
>>>>>
>>>>> bmdcapture -C 0 -m 14 -V 3 -A 2 -F nut -f pipe:1 | \
>>>>> avconv -y -i - -c:v libx264 -c:a aac -ar 44100 -strict experimental -s 640x360 -b:a 160k /pub/video/"$SHOW"_$TIME.mp4
>>>>>
>>>>> What would I have to do to stream to rtmp as well?
>>>>>
>>>>
>>>> Have a rtmp server somewhere (crtmpd is my current favourite) and
>>>> replace /pub/video/"$SHOW"_$TIME.mp4 with rtmp://serverhost/app/path/
>>>
>>> Understood, but I’m trying to write to both a file and a stream simultaneously.  
>>>
>>> I have this working…meaning, it starts, but rapidly fails after a few moments.  Here’s my current command line:
>>>
>>> bmdcapture -C 0 -m 14 -V 3 -A 2 -F nut -f pipe:1 | avconv -y -i - -copytb -c:v libx264 -c:a aac -ar 44100 -strict experimental -s 640x360 -b:a 160k /pub/video/"$SHOW"_$TIME.mp4 -f flv  -c:v libx264 -c:a aac -ar 22050 -strict experimental -s 384x216 -b:a 64k rtmp://live.mysite.com/myapp/video
>>>
>>> But it fails after some moments with this error:
>>>
>>> Stopping Capture 22 q=28.0 q=31.0 size= 5138kB time=62.48 bitrate= 673.6kbits/s
>>> Failed to update header with correct duration.0kB time=62.96 bitrate= 672.7kbits/s 
>>> [flv @ 0x248b7c0] Failed to update header with correct file size.
>>>
>>> Any clues as to what this is?
>>
>> Your system is too probably slow, add -preset ultrafast so x264 won’t
>> tax it too much.
> 
> Thanks.  Do I add this to the first x264 for the file or for the rtmp stream or both?
> 

Start with both then crank up the preset till it can be sustained.

lu



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