[FFmpeg-devel] mpeg2_metadata: Add support for A/53 caption extraction and removal

Submitted by Aman Gupta on March 12, 2018, 7:24 a.m.

Details

Message ID 20180312072400.26632-1-ffmpeg@tmm1.net
State New
Headers show

Commit Message

Aman Gupta March 12, 2018, 7:24 a.m.
From: Aman Gupta <aman@tmm1.net>

---
 doc/bitstream_filters.texi      | 12 +++++++
 libavcodec/mpeg2_metadata_bsf.c | 79 ++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 90 insertions(+), 1 deletion(-)

Comments

Aman Gupta March 12, 2018, 7:49 a.m.
On Mon, Mar 12, 2018 at 12:24 AM, Aman Gupta <ffmpeg@tmm1.net> wrote:

> From: Aman Gupta <aman@tmm1.net>
>
> ---
>  doc/bitstream_filters.texi      | 12 +++++++
>  libavcodec/mpeg2_metadata_bsf.c | 79 ++++++++++++++++++++++++++++++
> ++++++++++-
>  2 files changed, 90 insertions(+), 1 deletion(-)
>
> diff --git a/doc/bitstream_filters.texi b/doc/bitstream_filters.texi
> index b7ea549322..c0b48e62dc 100644
> --- a/doc/bitstream_filters.texi
> +++ b/doc/bitstream_filters.texi
> @@ -362,6 +362,18 @@ table 6-6).
>  Set the colour description in the stream (see H.262 section 6.3.6
>  and tables 6-7, 6-8 and 6-9).
>
> +@item a53_cc
> +Modify A/53 closed caption data in user data messages.
> +
> +@table @samp
> +@item remove
> +Remove all closed caption data from the stream.
> +
> +@item extract
> +Extract closed captions from the stream so that they are available as
> +as packet side data.
> +@end table
> +
>  @end table
>
>  @section mpeg4_unpack_bframes
> diff --git a/libavcodec/mpeg2_metadata_bsf.c b/libavcodec/mpeg2_metadata_
> bsf.c
> index 3bb6c1d549..0728ca4e09 100644
> --- a/libavcodec/mpeg2_metadata_bsf.c
> +++ b/libavcodec/mpeg2_metadata_bsf.c
> @@ -25,6 +25,12 @@
>  #include "cbs_mpeg2.h"
>  #include "mpeg12.h"
>
> +enum {
> +    PASS,
> +    REMOVE,
> +    EXTRACT,
> +};
> +
>  typedef struct MPEG2MetadataContext {
>      const AVClass *class;
>
> @@ -43,6 +49,7 @@ typedef struct MPEG2MetadataContext {
>      int matrix_coefficients;
>
>      int mpeg1_warned;
> +    int a53_cc;
>  } MPEG2MetadataContext;
>
>
> @@ -184,7 +191,9 @@ static int mpeg2_metadata_filter(AVBSFContext *bsf,
> AVPacket *out)
>      MPEG2MetadataContext *ctx = bsf->priv_data;
>      AVPacket *in = NULL;
>      CodedBitstreamFragment *frag = &ctx->fragment;
> -    int err;
> +    int err, i;
> +    uint8_t *a53_side_data = NULL;
> +    size_t a53_side_data_size = 0;
>
>      err = ff_bsf_get_packet(bsf, &in);
>      if (err < 0)
> @@ -202,6 +211,55 @@ static int mpeg2_metadata_filter(AVBSFContext *bsf,
> AVPacket *out)
>          goto fail;
>      }
>
> +    if (ctx->a53_cc == REMOVE || ctx->a53_cc == EXTRACT) {
> +        for (i = 0; i < frag->nb_units; i++) {
> +            MPEG2RawUserData *ud = NULL;
> +                uint32_t tag;
> +                uint8_t type_code, count;
> +
> +            if (frag->units[i].type != MPEG2_START_USER_DATA)
> +                continue;
> +            ud = frag->units[i].content;
> +            if (ud->user_data_length < 6)
> +                continue;
> +            tag = AV_RB32(ud->user_data);
> +            type_code = ud->user_data[4];
> +            if (tag != MKBETAG('G', 'A', '9', '4') || type_code != 3)
> +                continue;
> +
> +            if (ctx->a53_cc == REMOVE) {
> +                err = ff_cbs_delete_unit(ctx->cbc, frag, i);
> +                if (err < 0) {
> +                    av_log(bsf, AV_LOG_ERROR, "Failed to delete "
> +                           "A53 CC USER_DATA message.\n");
> +                    goto fail;
> +                }
> +                av_log(bsf, AV_LOG_WARNING, "A53 CC remove!.\n");
>

I changed these to TRACE locally, but I'll mimic whatever happens in the
h264_metadata version of the patch.


> +
> +                --i;
> +                break;
> +            }
> +
> +            // Extract.
> +            count = ud->user_data[5] & 0x1f;
> +            if (3 * count + 8 > ud->user_data_length) {
> +                av_log(bsf, AV_LOG_ERROR, "Invalid A/53 closed caption "
> +                       "data: count %d overflows length %zu.\n",
> +                       count, ud->user_data_length);
> +                continue;
> +            }
> +            av_log(bsf, AV_LOG_WARNING, "A53 CC extract: %zu bytes.\n",
> ud->user_data_length);
> +
> +            err = av_reallocp(&a53_side_data,
> +                              a53_side_data_size + 3 * count);
> +            if (err)
> +                goto fail;
> +            memcpy(a53_side_data + a53_side_data_size,
> +                   ud->user_data + 9, 3 * count);
>

This should be ud->user_data + 7. Fixed locally.


> +            a53_side_data_size += 3 * count;
> +        }
> +    }
> +
>      err = ff_cbs_write_packet(ctx->cbc, out, frag);
>      if (err < 0) {
>          av_log(bsf, AV_LOG_ERROR, "Failed to write packet.\n");
> @@ -214,9 +272,21 @@ static int mpeg2_metadata_filter(AVBSFContext *bsf,
> AVPacket *out)
>          goto fail;
>      }
>
> +    if (a53_side_data) {
> +        err = av_packet_add_side_data(out, AV_PKT_DATA_A53_CC,
> +                                      a53_side_data, a53_side_data_size);
> +        if (err) {
> +            av_log(bsf, AV_LOG_ERROR, "Failed to attach extracted A/53 "
> +                   "side data to packet.\n");
> +            goto fail;
> +        }
> +        a53_side_data = NULL;
> +    }
> +
>      err = 0;
>  fail:
>      ff_cbs_fragment_uninit(ctx->cbc, frag);
> +    av_freep(&a53_side_data);
>
>      av_packet_free(&in);
>
> @@ -288,6 +358,13 @@ static const AVOption mpeg2_metadata_options[] = {
>          OFFSET(matrix_coefficients), AV_OPT_TYPE_INT,
>          { .i64 = -1 }, -1, 255 },
>
> +    { "a53_cc", "A/53 Closed Captions in SEI NAL units",
> +        OFFSET(a53_cc), AV_OPT_TYPE_INT,
> +        { .i64 = PASS }, PASS, EXTRACT, 0, "a53_cc" },
> +    { "pass",    NULL, 0, AV_OPT_TYPE_CONST, { .i64 = PASS    }, .unit =
> "a53_cc" },
> +    { "remove",  NULL, 0, AV_OPT_TYPE_CONST, { .i64 = REMOVE  }, .unit =
> "a53_cc" },
> +    { "extract", NULL, 0, AV_OPT_TYPE_CONST, { .i64 = EXTRACT }, .unit =
> "a53_cc" },
> +
>      { NULL }
>  };
>
> --
> 2.14.2
>
>

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diff --git a/doc/bitstream_filters.texi b/doc/bitstream_filters.texi
index b7ea549322..c0b48e62dc 100644
--- a/doc/bitstream_filters.texi
+++ b/doc/bitstream_filters.texi
@@ -362,6 +362,18 @@  table 6-6).
 Set the colour description in the stream (see H.262 section 6.3.6
 and tables 6-7, 6-8 and 6-9).
 
+@item a53_cc
+Modify A/53 closed caption data in user data messages.
+
+@table @samp
+@item remove
+Remove all closed caption data from the stream.
+
+@item extract
+Extract closed captions from the stream so that they are available as
+as packet side data.
+@end table
+
 @end table
 
 @section mpeg4_unpack_bframes
diff --git a/libavcodec/mpeg2_metadata_bsf.c b/libavcodec/mpeg2_metadata_bsf.c
index 3bb6c1d549..0728ca4e09 100644
--- a/libavcodec/mpeg2_metadata_bsf.c
+++ b/libavcodec/mpeg2_metadata_bsf.c
@@ -25,6 +25,12 @@ 
 #include "cbs_mpeg2.h"
 #include "mpeg12.h"
 
+enum {
+    PASS,
+    REMOVE,
+    EXTRACT,
+};
+
 typedef struct MPEG2MetadataContext {
     const AVClass *class;
 
@@ -43,6 +49,7 @@  typedef struct MPEG2MetadataContext {
     int matrix_coefficients;
 
     int mpeg1_warned;
+    int a53_cc;
 } MPEG2MetadataContext;
 
 
@@ -184,7 +191,9 @@  static int mpeg2_metadata_filter(AVBSFContext *bsf, AVPacket *out)
     MPEG2MetadataContext *ctx = bsf->priv_data;
     AVPacket *in = NULL;
     CodedBitstreamFragment *frag = &ctx->fragment;
-    int err;
+    int err, i;
+    uint8_t *a53_side_data = NULL;
+    size_t a53_side_data_size = 0;
 
     err = ff_bsf_get_packet(bsf, &in);
     if (err < 0)
@@ -202,6 +211,55 @@  static int mpeg2_metadata_filter(AVBSFContext *bsf, AVPacket *out)
         goto fail;
     }
 
+    if (ctx->a53_cc == REMOVE || ctx->a53_cc == EXTRACT) {
+        for (i = 0; i < frag->nb_units; i++) {
+            MPEG2RawUserData *ud = NULL;
+                uint32_t tag;
+                uint8_t type_code, count;
+
+            if (frag->units[i].type != MPEG2_START_USER_DATA)
+                continue;
+            ud = frag->units[i].content;
+            if (ud->user_data_length < 6)
+                continue;
+            tag = AV_RB32(ud->user_data);
+            type_code = ud->user_data[4];
+            if (tag != MKBETAG('G', 'A', '9', '4') || type_code != 3)
+                continue;
+
+            if (ctx->a53_cc == REMOVE) {
+                err = ff_cbs_delete_unit(ctx->cbc, frag, i);
+                if (err < 0) {
+                    av_log(bsf, AV_LOG_ERROR, "Failed to delete "
+                           "A53 CC USER_DATA message.\n");
+                    goto fail;
+                }
+                av_log(bsf, AV_LOG_WARNING, "A53 CC remove!.\n");
+
+                --i;
+                break;
+            }
+
+            // Extract.
+            count = ud->user_data[5] & 0x1f;
+            if (3 * count + 8 > ud->user_data_length) {
+                av_log(bsf, AV_LOG_ERROR, "Invalid A/53 closed caption "
+                       "data: count %d overflows length %zu.\n",
+                       count, ud->user_data_length);
+                continue;
+            }
+            av_log(bsf, AV_LOG_WARNING, "A53 CC extract: %zu bytes.\n", ud->user_data_length);
+
+            err = av_reallocp(&a53_side_data,
+                              a53_side_data_size + 3 * count);
+            if (err)
+                goto fail;
+            memcpy(a53_side_data + a53_side_data_size,
+                   ud->user_data + 9, 3 * count);
+            a53_side_data_size += 3 * count;
+        }
+    }
+
     err = ff_cbs_write_packet(ctx->cbc, out, frag);
     if (err < 0) {
         av_log(bsf, AV_LOG_ERROR, "Failed to write packet.\n");
@@ -214,9 +272,21 @@  static int mpeg2_metadata_filter(AVBSFContext *bsf, AVPacket *out)
         goto fail;
     }
 
+    if (a53_side_data) {
+        err = av_packet_add_side_data(out, AV_PKT_DATA_A53_CC,
+                                      a53_side_data, a53_side_data_size);
+        if (err) {
+            av_log(bsf, AV_LOG_ERROR, "Failed to attach extracted A/53 "
+                   "side data to packet.\n");
+            goto fail;
+        }
+        a53_side_data = NULL;
+    }
+
     err = 0;
 fail:
     ff_cbs_fragment_uninit(ctx->cbc, frag);
+    av_freep(&a53_side_data);
 
     av_packet_free(&in);
 
@@ -288,6 +358,13 @@  static const AVOption mpeg2_metadata_options[] = {
         OFFSET(matrix_coefficients), AV_OPT_TYPE_INT,
         { .i64 = -1 }, -1, 255 },
 
+    { "a53_cc", "A/53 Closed Captions in SEI NAL units",
+        OFFSET(a53_cc), AV_OPT_TYPE_INT,
+        { .i64 = PASS }, PASS, EXTRACT, 0, "a53_cc" },
+    { "pass",    NULL, 0, AV_OPT_TYPE_CONST, { .i64 = PASS    }, .unit = "a53_cc" },
+    { "remove",  NULL, 0, AV_OPT_TYPE_CONST, { .i64 = REMOVE  }, .unit = "a53_cc" },
+    { "extract", NULL, 0, AV_OPT_TYPE_CONST, { .i64 = EXTRACT }, .unit = "a53_cc" },
+
     { NULL }
 };