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/*
* CEA-708 Closed Captioning FIFO
* Copyright (c) 2023 LTN Global Communications
*
* Author: Devin Heitmueller <dheitmueller@ltnglobal.com>
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "ccfifo.h"
#define MAX_CC_ELEMENTS 128
#define CC_BYTES_PER_ENTRY 3
struct cc_lookup {
int num;
int den;
int cc_count;
int num_608;
};
const static struct cc_lookup cc_lookup_vals[] = {
{ 15, 1, 40, 4 },
{ 24, 1, 25, 3 },
{ 24000, 1001, 25, 3 },
{ 30, 1, 20, 2 },
{ 30000, 1001, 20, 2},
{ 60, 1, 10, 1 },
{ 60000, 1001, 10, 1},
};
void ff_ccfifo_uninit(CCFifo *ccf)
{
av_fifo_freep2(&ccf->cc_608_fifo);
av_fifo_freep2(&ccf->cc_708_fifo);
memset(ccf, 0, sizeof(*ccf));
}
int ff_ccfifo_init(CCFifo *ccf, AVRational framerate, void *log_ctx)
{
int i;
memset(ccf, 0, sizeof(*ccf));
ccf->log_ctx = log_ctx;
ccf->framerate = framerate;
if (!(ccf->cc_708_fifo = av_fifo_alloc2(MAX_CC_ELEMENTS, CC_BYTES_PER_ENTRY, 0)))
goto error;
if (!(ccf->cc_608_fifo = av_fifo_alloc2(MAX_CC_ELEMENTS, CC_BYTES_PER_ENTRY, 0)))
goto error;
/* Based on the target FPS, figure out the expected cc_count and number of
608 tuples per packet. See ANSI/CTA-708-E Sec 4.3.6.1. */
for (i = 0; i < FF_ARRAY_ELEMS(cc_lookup_vals); i++) {
if (framerate.num == cc_lookup_vals[i].num &&
framerate.den == cc_lookup_vals[i].den) {
ccf->expected_cc_count = cc_lookup_vals[i].cc_count;
ccf->expected_608 = cc_lookup_vals[i].num_608;
break;
}
}
if (ccf->expected_608 == 0) {
/* We didn't find an output frame we support. We'll let the call succeed
and the FIFO to be allocated, but the extract/inject functions will simply
leave everything the way it is */
ccf->passthrough = 1;
}
return 0;
error:
ff_ccfifo_uninit(ccf);
return AVERROR(ENOMEM);
}
int ff_ccfifo_getoutputsize(const CCFifo *ccf)
{
return ccf->expected_cc_count * CC_BYTES_PER_ENTRY;
}
int ff_ccfifo_ccdetected(const CCFifo *ccf)
{
return ccf->cc_detected;
}
int ff_ccfifo_injectbytes(CCFifo *ccf, uint8_t *cc_data, size_t len)
{
int cc_608_tuples = 0;
int cc_708_tuples = 0;
int cc_filled = 0;
if (ccf->passthrough) {
return 0;
}
if (len < ff_ccfifo_getoutputsize(ccf)) {
return AVERROR(EINVAL);
}
/* Insert any available data from the 608 FIFO */
if (ccf->expected_608 <= av_fifo_can_read(ccf->cc_608_fifo))
cc_608_tuples = ccf->expected_608;
else
cc_608_tuples = av_fifo_can_read(ccf->cc_608_fifo);
av_fifo_read(ccf->cc_608_fifo, cc_data, cc_608_tuples);
cc_filled += cc_608_tuples;
/* Insert any available data from the 708 FIFO */
if ((ccf->expected_cc_count - cc_filled) <= av_fifo_can_read(ccf->cc_708_fifo))
cc_708_tuples = ccf->expected_cc_count - cc_filled;
else
cc_708_tuples = av_fifo_can_read(ccf->cc_708_fifo);
av_fifo_read(ccf->cc_708_fifo, &cc_data[cc_filled * CC_BYTES_PER_ENTRY], cc_708_tuples);
cc_filled += cc_708_tuples;
/* Insert 708 padding into any remaining fields */
while (cc_filled < ccf->expected_cc_count) {
cc_data[cc_filled * CC_BYTES_PER_ENTRY] = 0xfa;
cc_data[cc_filled * CC_BYTES_PER_ENTRY + 1] = 0x00;
cc_data[cc_filled * CC_BYTES_PER_ENTRY + 2] = 0x00;
cc_filled++;
}
return 0;
}
int ff_ccfifo_inject(CCFifo *ccf, AVFrame *frame)
{
AVFrameSideData *sd;
int ret;
if (ccf->passthrough == 1 || ccf->cc_detected == 0)
return 0;
sd = av_frame_new_side_data(frame, AV_FRAME_DATA_A53_CC,
ff_ccfifo_getoutputsize(ccf));
if (sd) {
ret = ff_ccfifo_injectbytes(ccf, sd->data, sd->size);
if (ret < 0) {
av_frame_remove_side_data(frame, AV_FRAME_DATA_A53_CC);
return ret;
}
}
return 0;
}
int ff_ccfifo_extractbytes(CCFifo *ccf, uint8_t *cc_bytes, size_t len)
{
int cc_count = len / CC_BYTES_PER_ENTRY;
if (ccf->passthrough == 1) {
av_log_once(ccf->log_ctx, AV_LOG_WARNING, AV_LOG_DEBUG, &ccf->passthrough_warning,
"cc_fifo cannot transcode captions fps=%d/%d\n",
ccf->framerate.num, ccf->framerate.den);
return 0;
}
ccf->cc_detected = 1;
for (int i = 0; i < cc_count; i++) {
/* See ANSI/CTA-708-E Sec 4.3, Table 3 */
uint8_t cc_valid = (cc_bytes[CC_BYTES_PER_ENTRY*i] & 0x04) >> 2;
uint8_t cc_type = cc_bytes[CC_BYTES_PER_ENTRY*i] & 0x03;
if (cc_type == 0x00 || cc_type == 0x01) {
av_fifo_write(ccf->cc_608_fifo, &cc_bytes[CC_BYTES_PER_ENTRY*i], 1);
} else if (cc_valid && (cc_type == 0x02 || cc_type == 0x03)) {
av_fifo_write(ccf->cc_708_fifo, &cc_bytes[CC_BYTES_PER_ENTRY*i], 1);
}
}
return 0;
}
/* Read the A53 side data, discard padding, and put 608/708 into
queues so we can ensure they get into the output frames at
the correct rate... */
int ff_ccfifo_extract(CCFifo *ccf, AVFrame *frame)
{
AVFrameSideData *side_data = av_frame_get_side_data(frame, AV_FRAME_DATA_A53_CC);
if (side_data) {
ff_ccfifo_extractbytes(ccf, side_data->data, side_data->size);
/* Remove the side data, as we will re-create it on the
output as needed */
if (!ccf->passthrough)
av_frame_remove_side_data(frame, AV_FRAME_DATA_A53_CC);
}
return 0;
}
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