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/*
* MXF SMPTE-436M ANC to EIA-608 bitstream filter
* Copyright (c) 2025 Jacob Lifshay
*
* 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 "bsf.h"
#include "bsf_internal.h"
#include "codec_id.h"
#include "libavcodec/smpte_436m.h"
#include "libavutil/error.h"
static av_cold int ff_smpte436m_to_eia608_init(AVBSFContext *ctx)
{
ctx->par_out->codec_type = AVMEDIA_TYPE_SUBTITLE;
ctx->par_out->codec_id = AV_CODEC_ID_EIA_608;
return 0;
}
static int ff_smpte436m_to_eia608_filter(AVBSFContext *ctx, AVPacket *out)
{
AVPacket *in;
int ret = ff_bsf_get_packet(ctx, &in);
if (ret < 0)
return ret;
AVSmpte436mAncIterator iter;
ret = av_smpte_436m_anc_iter_init(&iter, in->data, in->size);
if (ret < 0)
goto fail;
AVSmpte436mCodedAnc coded_anc;
while ((ret = av_smpte_436m_anc_iter_next(&iter, &coded_anc)) >= 0) {
AVSmpte291mAnc8bit anc;
ret = av_smpte_291m_anc_8bit_decode(
&anc, coded_anc.payload_sample_coding, coded_anc.payload_sample_count, coded_anc.payload, ctx);
if (ret < 0)
goto fail;
ret = av_smpte_291m_anc_8bit_extract_cta_708(&anc, NULL, ctx);
if (ret == AVERROR(EAGAIN))
continue;
if (ret < 0)
goto fail;
int cc_count = ret;
ret = av_new_packet(out, 3 * cc_count);
if (ret < 0)
goto fail;
ret = av_packet_copy_props(out, in);
if (ret < 0)
goto fail;
// verified it won't fail by running it above
av_smpte_291m_anc_8bit_extract_cta_708(&anc, out->data, ctx);
av_packet_free(&in);
return 0;
}
if (ret != AVERROR_EOF)
return ret;
ret = AVERROR(EAGAIN);
fail:
if (ret < 0)
av_packet_unref(out);
av_packet_free(&in);
return ret;
}
const FFBitStreamFilter ff_smpte436m_to_eia608_bsf = {
.p.name = "smpte436m_to_eia608",
.p.codec_ids = (const enum AVCodecID[]){ AV_CODEC_ID_SMPTE_436M_ANC, AV_CODEC_ID_NONE },
.init = ff_smpte436m_to_eia608_init,
.filter = ff_smpte436m_to_eia608_filter,
};
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