[FFmpeg-devel] [PATCH v4 5/7] avformat/movenc: utilize existing AC-3 parsing workflow for AC-3
Andreas Rheinhardt
andreas.rheinhardt at outlook.com
Thu Jun 23 11:56:45 EEST 2022
Jan Ekström:
> From: Jan Ekström <jan.ekstrom at 24i.com>
>
> Signed-off-by: Jan Ekström <jan.ekstrom at 24i.com>
> ---
> libavcodec/Makefile | 1 +
> libavformat/Makefile | 1 +
> libavformat/ac3_bitrate_tab.c | 22 ++++++++++++++
> libavformat/movenc.c | 55 +++++++++++++++++------------------
> 4 files changed, 51 insertions(+), 28 deletions(-)
> create mode 100644 libavformat/ac3_bitrate_tab.c
>
> diff --git a/libavcodec/Makefile b/libavcodec/Makefile
> index 10697d31f7..7e0d278e3d 100644
> --- a/libavcodec/Makefile
> +++ b/libavcodec/Makefile
> @@ -1018,6 +1018,7 @@ STLIBOBJS-$(CONFIG_FLV_MUXER) += mpeg4audio_sample_rates.o
> STLIBOBJS-$(CONFIG_HLS_DEMUXER) += ac3_channel_layout_tab.o
> STLIBOBJS-$(CONFIG_MATROSKA_DEMUXER) += mpeg4audio_sample_rates.o
> STLIBOBJS-$(CONFIG_MOV_DEMUXER) += ac3_channel_layout_tab.o
> +STLIBOBJS-$(CONFIG_MOV_MUXER) += ac3_bitrate_tab.o
> STLIBOBJS-$(CONFIG_MXF_MUXER) += golomb.o
> STLIBOBJS-$(CONFIG_MP3_MUXER) += mpegaudiotabs.o
> STLIBOBJS-$(CONFIG_NUT_MUXER) += mpegaudiotabs.o
> diff --git a/libavformat/Makefile b/libavformat/Makefile
> index 1416bf31bd..c71de95b2f 100644
> --- a/libavformat/Makefile
> +++ b/libavformat/Makefile
> @@ -699,6 +699,7 @@ SHLIBOBJS-$(CONFIG_FLV_MUXER) += mpeg4audio_sample_rates.o
> SHLIBOBJS-$(CONFIG_HLS_DEMUXER) += ac3_channel_layout_tab.o
> SHLIBOBJS-$(CONFIG_MATROSKA_DEMUXER) += mpeg4audio_sample_rates.o
> SHLIBOBJS-$(CONFIG_MOV_DEMUXER) += ac3_channel_layout_tab.o
> +SHLIBOBJS-$(CONFIG_MOV_MUXER) += ac3_bitrate_tab.o
> SHLIBOBJS-$(CONFIG_MP3_MUXER) += mpegaudiotabs.o
> SHLIBOBJS-$(CONFIG_MXF_MUXER) += golomb_tab.o
> SHLIBOBJS-$(CONFIG_NUT_MUXER) += mpegaudiotabs.o
> diff --git a/libavformat/ac3_bitrate_tab.c b/libavformat/ac3_bitrate_tab.c
> new file mode 100644
> index 0000000000..57b6181511
> --- /dev/null
> +++ b/libavformat/ac3_bitrate_tab.c
> @@ -0,0 +1,22 @@
> +/*
> + * AC-3 bit rate table
> + * copyright (c) 2001 Fabrice Bellard
> + *
> + * 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 "libavcodec/ac3_bitrate_tab.h"
> diff --git a/libavformat/movenc.c b/libavformat/movenc.c
> index 103f958d75..a071f1cdd5 100644
> --- a/libavformat/movenc.c
> +++ b/libavformat/movenc.c
> @@ -36,6 +36,7 @@
> #include "av1.h"
> #include "avc.h"
> #include "libavcodec/ac3_parser_internal.h"
> +#include "libavcodec/ac3tab.h"
> #include "libavcodec/dnxhddata.h"
> #include "libavcodec/flac.h"
> #include "libavcodec/get_bits.h"
> @@ -362,44 +363,42 @@ struct eac3_info {
>
> static int mov_write_ac3_tag(AVFormatContext *s, AVIOContext *pb, MOVTrack *track)
> {
> - GetBitContext gbc;
> + struct eac3_info *info = track->eac3_priv;
> + int8_t ac3_bit_rate_code = -1;
> PutBitContext pbc;
> uint8_t buf[3];
> - int fscod, bsid, bsmod, acmod, lfeon, frmsizecod;
>
> - if (track->vos_len < 7) {
> + if (!info || !info->ec3_done) {
> av_log(s, AV_LOG_ERROR,
> "Cannot write moov atom before AC3 packets."
> " Set the delay_moov flag to fix this.\n");
> return AVERROR(EINVAL);
> }
>
> - avio_wb32(pb, 11);
> - ffio_wfourcc(pb, "dac3");
> + for (unsigned int i = 0; i < FF_ARRAY_ELEMS(ff_ac3_bitrate_tab); i++) {
> + if (info->data_rate == ff_ac3_bitrate_tab[i]) {
> + ac3_bit_rate_code = i;
> + break;
> + }
> + }
Why don't you just export the bit rate code instead of rederiving it?
This should be easy now that you intend to disallow AC-3 frames with
bsid > 8.
>
> - init_get_bits(&gbc, track->vos_data + 4, (track->vos_len - 4) * 8);
> - fscod = get_bits(&gbc, 2);
> - frmsizecod = get_bits(&gbc, 6);
> - bsid = get_bits(&gbc, 5);
> - bsmod = get_bits(&gbc, 3);
> - acmod = get_bits(&gbc, 3);
> - if (acmod == 2) {
> - skip_bits(&gbc, 2); // dsurmod
> - } else {
> - if ((acmod & 1) && acmod != 1)
> - skip_bits(&gbc, 2); // cmixlev
> - if (acmod & 4)
> - skip_bits(&gbc, 2); // surmixlev
> + if (ac3_bit_rate_code < 0) {
> + av_log(s, AV_LOG_ERROR,
> + "No valid AC3 bit rate code for data rate of %d!\n",
> + info->data_rate);
> + return AVERROR(EINVAL);
> }
> - lfeon = get_bits1(&gbc);
> +
> + avio_wb32(pb, 11);
> + ffio_wfourcc(pb, "dac3");
>
> init_put_bits(&pbc, buf, sizeof(buf));
> - put_bits(&pbc, 2, fscod);
> - put_bits(&pbc, 5, bsid);
> - put_bits(&pbc, 3, bsmod);
> - put_bits(&pbc, 3, acmod);
> - put_bits(&pbc, 1, lfeon);
> - put_bits(&pbc, 5, frmsizecod >> 1); // bit_rate_code
> + put_bits(&pbc, 2, info->substream[0].fscod);
> + put_bits(&pbc, 5, info->substream[0].bsid);
> + put_bits(&pbc, 3, info->substream[0].bsmod);
> + put_bits(&pbc, 3, info->substream[0].acmod);
> + put_bits(&pbc, 1, info->substream[0].lfeon);
> + put_bits(&pbc, 5, ac3_bit_rate_code); // bit_rate_code
> put_bits(&pbc, 5, 0); // reserved
>
> flush_put_bits(&pbc);
> @@ -5975,8 +5974,7 @@ int ff_mov_write_packet(AVFormatContext *s, AVPacket *pkt)
> if ((par->codec_id == AV_CODEC_ID_DNXHD ||
> par->codec_id == AV_CODEC_ID_H264 ||
> par->codec_id == AV_CODEC_ID_HEVC ||
> - par->codec_id == AV_CODEC_ID_TRUEHD ||
> - par->codec_id == AV_CODEC_ID_AC3) && !trk->vos_len &&
> + par->codec_id == AV_CODEC_ID_TRUEHD) && !trk->vos_len &&
> !TAG_IS_AVCI(trk->tag)) {
> /* copy frame to create needed atoms */
> trk->vos_len = size;
> @@ -6053,7 +6051,8 @@ int ff_mov_write_packet(AVFormatContext *s, AVPacket *pkt)
> }
> }
>
> - } else if (par->codec_id == AV_CODEC_ID_EAC3) {
> + } else if (par->codec_id == AV_CODEC_ID_EAC3 ||
> + par->codec_id == AV_CODEC_ID_AC3) {
> size = handle_eac3(mov, pkt, trk);
> if (size < 0)
> return size;
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