static int dv_write_header(AVFormatContext *s) { s->priv_data = dv_init_mux(s); if (!s->priv_data) { av_log(s, AV_LOG_ERROR, "Can't initialize DV format!\n" "Make sure that you supply exactly two streams:\n" " video: 25fps or 29.97fps, audio: 2ch/48Khz/PCM\n" " (50Mbps allows an optional second audio stream)\n"); return -1; } return 0; }