[FFmpeg-user] ffmpeg extremely high consumption

[Pavel Koshevoy]

On 6/13/15 17:49, En Figureo Canal wrote:
> On Sat, Jun 13, 2015 at 8:24 PM, Moritz Barsnick <barsnick at gmx.net> wrote:
>
>> On Sat, Jun 13, 2015 at 19:17:51 -0400, En Figureo Canal wrote:
>>> Noticed that, after Henk's reply, if I use -vcodec copy then the output
>>> will "copy" the source video's attribute (-vb, size, etc...), but, if I
>>> really need to set the video rate (-vb) then I need to specify the codec
>>> needed to encode the new video.
>> No, it does not copy the attributes (those are very had to duplicate),
>> it copies the stream without reencoding. You wouldn't even need libx264
>> for that.
>>
>>   <http://ffmpeg.org/mailman/listinfo/ffmpeg-user>
>>
> I understand I don't need libx264 but, when I tried it like this:
>
> ffmpeg -i video.mp4 -vcodec copy -vb 1024k -f flv rtmp://ip/live/test
>
> the output rate was the original video rate at 4M
>
> But, if I do this:
>
> ffmpeg -i video.mp4 -vcodec libx264 -vb 1024k  -f flv rtmp://ip/live/test
>
> the output rate is at 1M but video freezes.

You either need a faster computer, or a hardware accelerated encoder 
(nvenc if you have compatible NVIDIA card), or you can use a less 
demanding libx264 preset -- "veryfast" might work, "ultrafast" is most 
likely to work.  I believe the default is "medium".  The cheapest and 
quickest thing you can try is adding -preset ultrafast after libx264.  
If you don't like the quality try -preset veryfast. If that fails 
consider using nvenc.

Also, see here -- https://trac.ffmpeg.org/wiki/EncodingForStreamingSites 
-- it appears to be relevant to what you are trying to do.

     Pavel.