[FFmpeg-user] How to display Close Caption on the screen

[Micael Silva]

On Thu, Oct 25, 2018 at 10:22 AM Erik Gaudin <erik.gaudin at cbc.ca> wrote:

> When i open our internal stream with VLC, i can displayed Substitle. But
> can't find how to do it with ffplay.exe (windows)
>
> ffplay udp://@239.255.123.1:1234 -analyzeduration 200
> I use the last argument for low latency.
>
> Here what appear in DOS when start FFPLAY with URL only :
>
> Input #0, mpegts, from 'udp://@239.255.179.6:5000':q=    0B f=0/0
>   Duration: N/A, start: 86892.634178, bitrate: N/A
>   Program 2672
>     Stream #0:0[0xa72]: Video: hevc (Main) ([36][0][0][0] / 0x0024),
> yuv420p(tv), 1280x720 [SAR 1:1 DAR 16:9], Closed Captions, 59.94 fps, 59.94
> tbr, 90k tbn, 59.94 tbc
>     Stream #0:1[0xa73](eng): Audio: aac_latm (LC) ([17][0][0][0] / 0x0011),
> 48000 Hz, stereo, fltp
>     Stream #0:2[0xa74](fre): Audio: aac_latm (LC) ([17][0][0][0] / 0x0011),
> 48000 Hz, stereo, fltp
>
>
> In VLC, CC are in Flux # 3  (Flux 0 = video, Flux 1 & 2 Audio track)
>
>
>
>
> Erik Gaudin
> Chef de projet
> Société Radio-Canada (SRC)
> Ingénierie Médias (Montréal)
>
>
> Project Leader
> Canadian Broadcasting Corporation (CBC)
> Media Engineering (Montreal)
>
>
> Tél. : 514-597-6586 (1-141-6586)
> Cell. : 514-895-6586
>

FFmpeg and FFplay as far as I know only displays natively subtitle formats
that is pre-rendereded images such as DVD subtitles. Text formats like SRT,
ASS are shown using filters like subtile that renders the text using
libraries like libfreetype and then piping to display or file. Maybe there
is a way to get the text from closed captions and render it, but being
inside h264 frames like this case makes it a little tricky