[FFmpeg-user] Receive network stream and drop without decoding

[Andrius Narbutas]

On 2020-06-15 23:58, Carl Eugen Hoyos wrote:
> $ ffmpeg -i input -map 0:a:0 -c copy -f null -

ffmpeg -i 
http://download.tsi.telecom-paristech.fr/gpac/dataset/dash/uhd/dashevc-ondemand-4s/dashevc-ondemand-4s-p60.mpd 
-map 0:a:0 -c copy -f null -
<...>
size=N/A time=00:02:31.80 bitrate=N/A speed= 165x
video:0kB audio:1195kB subtitle:0kB other streams:0kB global headers:0kB 
muxing overhead: unknown
...and quits
So, it just pulls one DASH audio chunk into null sink and exits (no 
re-request, also note video:0kB)

> Other possibilities like -map 0:0 exist.

Slightly better as now it takes video, too:
ffmpeg -i 
http://download.tsi.telecom-paristech.fr/gpac/dataset/dash/uhd/dashevc-ondemand-4s/dashevc-ondemand-4s-p60.mpd 
-map 0:0 -c copy -f null -
<...>
frame= 4320 fps=197 q=-1.0 Lsize=N/A time=00:02:19.93 bitrate=N/A 
speed=6.37x
video:24094kB audio:0kB subtitle:0kB other streams:0kB global 
headers:0kB muxing overhead: unknown
Now it pulls one chunk of video (but not audio stream), pushes to null 
sink and exits.

With -map 0:a:0 -map 0:v:0 ir pulls audio and video, but again only one 
chunk, does not follow stream. With -v debug it does not tell story why 
it decided to not take next chunk...

CPU load during this one step is low, so probably no decoding done.