[FFmpeg-cvslog] avcodec: split off A53 Closed Caption parsing code into its own file
James Almer
git at videolan.org
Sat Aug 15 19:01:57 EEST 2020
ffmpeg | branch: master | James Almer <jamrial at gmail.com> | Fri Aug 7 16:03:29 2020 -0300| [184192127701243de18111e37120a37637321f64] | committer: James Almer
avcodec: split off A53 Closed Caption parsing code into its own file
Signed-off-by: James Almer <jamrial at gmail.com>
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=184192127701243de18111e37120a37637321f64
---
configure | 1 +
libavcodec/Makefile | 1 +
libavcodec/atsc_a53.c | 76 +++++++++++++++++++++++++++++++++++++++++++++++++++
libavcodec/atsc_a53.h | 39 ++++++++++++++++++++++++++
4 files changed, 117 insertions(+)
diff --git a/configure b/configure
index d4a1fea9ce..34c40a765a 100755
--- a/configure
+++ b/configure
@@ -2344,6 +2344,7 @@ CONFIG_EXTRA="
aandcttables
ac3dsp
adts_header
+ atsc_a53
audio_frame_queue
audiodsp
blockdsp
diff --git a/libavcodec/Makefile b/libavcodec/Makefile
index fc4294816e..3431ba2dca 100644
--- a/libavcodec/Makefile
+++ b/libavcodec/Makefile
@@ -64,6 +64,7 @@ OBJS-$(CONFIG_AC3DSP) += ac3dsp.o ac3.o ac3tab.o
OBJS-$(CONFIG_ADTS_HEADER) += adts_header.o mpeg4audio.o
OBJS-$(CONFIG_AMF) += amfenc.o
OBJS-$(CONFIG_AUDIO_FRAME_QUEUE) += audio_frame_queue.o
+OBJS-$(CONFIG_ATSC_A53) += atsc_a53.o
OBJS-$(CONFIG_AUDIODSP) += audiodsp.o
OBJS-$(CONFIG_BLOCKDSP) += blockdsp.o
OBJS-$(CONFIG_BSWAPDSP) += bswapdsp.o
diff --git a/libavcodec/atsc_a53.c b/libavcodec/atsc_a53.c
new file mode 100644
index 0000000000..b2d1490c0c
--- /dev/null
+++ b/libavcodec/atsc_a53.c
@@ -0,0 +1,76 @@
+/*
+ * 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 <stddef.h>
+#include <stdint.h>
+
+#include "atsc_a53.h"
+#include "get_bits.h"
+
+int ff_parse_a53_cc(AVBufferRef **pbuf, const uint8_t *data, int size)
+{
+ AVBufferRef *buf = *pbuf;
+ GetBitContext gb;
+ size_t new_size, old_size = buf ? buf->size : 0;
+ int ret, cc_count;
+
+ if (size < 3)
+ return AVERROR(EINVAL);
+
+ ret = init_get_bits8(&gb, data, size);
+ if (ret < 0)
+ return ret;
+
+ if (get_bits(&gb, 8) != 0x3) // user_data_type_code
+ return 0;
+
+ skip_bits(&gb, 1); // reserved
+ if (!get_bits(&gb, 1)) // process_cc_data_flag
+ return 0;
+
+ skip_bits(&gb, 1); // zero bit
+ cc_count = get_bits(&gb, 5);
+ if (!cc_count)
+ return 0;
+
+ skip_bits(&gb, 8); // reserved
+
+ /* 3 bytes per CC plus one byte marker_bits at the end */
+ if (cc_count * 3 >= (get_bits_left(&gb) >> 3))
+ return AVERROR(EINVAL);
+
+ new_size = (old_size + cc_count * 3);
+
+ if (new_size > INT_MAX)
+ return AVERROR(EINVAL);
+
+ /* Allow merging of the cc data from two fields. */
+ ret = av_buffer_realloc(pbuf, new_size);
+ if (ret < 0)
+ return ret;
+
+ buf = *pbuf;
+ /* Use of av_buffer_realloc assumes buffer is writeable */
+ for (int i = 0; i < cc_count; i++) {
+ buf->data[old_size++] = get_bits(&gb, 8);
+ buf->data[old_size++] = get_bits(&gb, 8);
+ buf->data[old_size++] = get_bits(&gb, 8);
+ }
+
+ return cc_count;
+}
diff --git a/libavcodec/atsc_a53.h b/libavcodec/atsc_a53.h
new file mode 100644
index 0000000000..a419d801b9
--- /dev/null
+++ b/libavcodec/atsc_a53.h
@@ -0,0 +1,39 @@
+/*
+ * 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
+ */
+
+#ifndef AVCODEC_ATSC_A53_H
+#define AVCODEC_ATSC_A53_H
+
+#include <stdint.h>
+
+#include "libavutil/buffer.h"
+
+/**
+ * Parse a data array for ATSC A53 Part 4 Closed Captions and store them in an AVBufferRef.
+ *
+ * @param pbuf Pointer to an AVBufferRef to append the closed captions. *pbuf may be NULL, in
+ * which case a new buffer will be allocated and put in it.
+ * @param data The data array containing the raw A53 data.
+ * @param size Size of the data array in bytes.
+ *
+ * @return Number of closed captions parsed on success, negative error code on failure.
+ * If no Closed Captions are parsed, *pbuf is untouched.
+ */
+int ff_parse_a53_cc(AVBufferRef **pbuf, const uint8_t *data, int size);
+
+#endif /* AVCODEC_ATSC_A53_H */
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