Show decoded caption data in Caption viewer

[iamdamosuzuki]

I would like to have the option to view the decoded caption data in the Caption Viewer mode, rather than the raw hex values.

[dericed]

Hmm, I'm not sure how to get ffmpeg to do this, cc'ing @richardpl for advice.

Currently the caption values as accessible in their hexadecimal form via the metadata filter (as used at

vrecord/vrecord

Line 551 in e933bd8

CAPTION_WRITE=",readeia608=lp=1:spw=0.27,metadata=mode=print:key=lavfi.readeia608.0.cc:file=${CAPTION_TMP}"

) and then output to a file. Then a function processes that metadata output from those hex values into an scc (

vrecord/vrecord

Lines 265 to 340 in e933bd8

	_eia608dump2scc(){
	EIA608DUMP_IN="${1}"
	SCC_OUT="${2}"
	_smmm_to_hhmmssff(){
	secs="$1"
	echo "${secs}" | awk '{ printf "%02i:%02i:%02i:%02i\n", $1/60/60, $1/60%60, $1%60, $1%1*30 }'
	}
	_write_cc(){
	CC="$1"
	if [[ "$START" == "Y" ]] ; then
	echo -n " ${CC}" >> "${SCC_OUT}"
	else
	echo -n " ${CC}" >> "${SCC_OUT}"
	fi
	START="N"
	}
	_write_new_cc_line(){
	SCC_TIME="$(_smmm_to_hhmmssff "${SECS}")"
	echo -e -n "\n\n${SCC_TIME}" >> "${SCC_OUT}"
	START="Y"
	}
	_start_scc(){
	echo -n "Scenarist_SCC V1.0" > "${SCC_OUT}"
	}
	_end_scc(){
	echo >> "${SCC_OUT}"
	}
	#initialize
	PREV_CC="8080"
	CC_PRESENT=0
	REPORT=0
	_start_scc
	while read METADATA_LINE ; do
	if [[ "${METADATA_LINE:0:8}" == "pts_time" ]] ; then
	SECS="${METADATA_LINE/pts_time:}"
	REPORT=0
	elif [[ "${METADATA_LINE:0:21}" == "lavfi.readeia608.0.cc" ]] ; then
	CC_HEX="${METADATA_LINE/lavfi.readeia608.0.cc=}"
	REPORT=1
	if [[ -n "${CC_HEX}" && "${REPORT}" ]] ; then
	CC="${CC_HEX:2:4}"
	if { [[ "${CC}" != "8080" ]] && [[ "${PREV_CC}" == "8080" ]] ; } || { [[ "${CC}" == "9420" ]] && [[ "${PREV_CC}" != "9420" ]] ; } ; then
	_write_new_cc_line
	_write_cc "$CC"
	elif [[ "${CC}" != "8080" ]] ; then
	_write_cc "$CC"
	fi
	PREV_CC="$CC"
	if [[ "$CC_PRESENT" == 0 ]] ; then
	CC_PRESENT=1
	if [[ -n "${CC_LOG}" ]] ; then
	TRANSITION_TIME="$(_smmm_to_hhmmssff "${SECS}")"
	_report -d "${CC_LOG} - ${TRANSITION_TIME}."
	fi
	TRANSITION_TIME="$(_smmm_to_hhmmssff "${SECS}")"
	CC_LOG="Caption data ON: ${TRANSITION_TIME}"
	fi
	else
	if [[ "$CC_PRESENT" == 1 ]] ; then
	CC_PRESENT=0
	if [[ -n "${CC_LOG}" ]] ; then
	TRANSITION_TIME="$(_smmm_to_hhmmssff "${SECS}")"
	_report -d "${CC_LOG} - ${TRANSITION_TIME}."
	fi
	TRANSITION_TIME="$(_smmm_to_hhmmssff "${SECS}")"
	CC_LOG="Caption data OFF: ${TRANSITION_TIME}"
	fi
	PREV_CC="8080"
	fi
	PREV_SECS="$SECS"
	fi
	done < <(grep -o "pts_time:[^ ]*\|lavfi.readeia608.0.cc=[^ ]*" "${EIA608DUMP_IN}")
	_end_scc
	}

, this is borrowed from sccyou).

To get onscreen captions for a live input, then the output of the metadata filter would need to be sent back to ffmpeg as an additional input. I see that ffmpeg has an 608 decoder but I'm uncertain how to accept that as an input as there's no -f rawdata -c eia608 options.

[richardpl]

You could write .scc files and use .scc demuxer from libavformat, if you instead need realtime/stream solution than its more complex.