[Libav-user] help with raw fifo as movie src & overlay

gstream at ccc2.com gstream at ccc2.com
Mon Feb 13 11:31:04 CET 2012

Hi All,

I am hoping you can help with getting the libavfilter movie and overlay
working correctly.

My objective is to get two RTSP camera feeds to go side by side in sync.

I started with the below that works to transmit the final image but due to
the loading times of each overlay the streams are out of sync.

ffmpeg  -loop_input -i 800x600.jpg -an -s 1288x360 -vf
[in][wm] overlay=2:4[in+wm];
[in+wm][wm2] overlay=646:4 [out]'
-s 1288x360 -vcodec rawvideo /home/fifo/mpegpipe99.yuv

so firstly, is there a way I can add a video buffer to the first overlay
so it syncs with the second?

If not, can I use rawvideo from upstream ffmpeg's. I am assuming that by
having upstream decoders the sink going into the overlay's will be the

I have tried several ways to get the rawvideo to load but an diff error
returns every time. The below....

ffmpeg  -loop_input -i 1280x720.jpg -an -s 1288x360 -vf
'movie=/home/fifo/mpegpipe1.yuv,buffer=640:352:yuv420p:1:25:1:1 [wm];
 movie=/home/fifo/mpegpipe2.yuv,buffer=640:354:yuv420p:1:25:1:1 [wm2];
[in][wm] overlay=2:4[in+wm]; [in+wm][wm2]  overlay=646:4 [out]'  -vcodec
rawvideo /home/zorobigz_2/fifo/mpegpipe99.yuv -s 1280x360

generates the following error.....

[movie @ 0x1ab6b00] seek_point:0 format_name:(null)
file_name:/home/fifo/mpegpipe1.yuv stream_index:0
[buffer @ 0x1ab6a80] w:640 h:352 pixfmt:yuv420p tb:1/25 sar:1/1 sws_param:
Too many inputs specified for the "buffer" filter.

this does seem to be the right number of params as per the doc's.

your help would be very much appreciated.

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