[FFmpeg-devel] [PATCH 07/27] cbs: Implement common parts of cbs-based bitstream filters separately

Andreas Rheinhardt andreas.rheinhardt at gmail.com
Sat Jan 2 00:18:13 EET 2021


Mark Thompson:
> This allows removal of a lot of duplicated code between BSFs.
> ---
>  libavcodec/Makefile  |   2 +-
>  libavcodec/cbs_bsf.c | 161 +++++++++++++++++++++++++++++++++++++++++++
>  libavcodec/cbs_bsf.h | 100 +++++++++++++++++++++++++++
>  3 files changed, 262 insertions(+), 1 deletion(-)
>  create mode 100644 libavcodec/cbs_bsf.c
>  create mode 100644 libavcodec/cbs_bsf.h
> 
> diff --git a/libavcodec/Makefile b/libavcodec/Makefile
> index 6e12a8171d..8f50217ad4 100644
> --- a/libavcodec/Makefile
> +++ b/libavcodec/Makefile
> @@ -69,7 +69,7 @@ OBJS-$(CONFIG_AUDIODSP)                += audiodsp.o
>  OBJS-$(CONFIG_BLOCKDSP)                += blockdsp.o
>  OBJS-$(CONFIG_BSWAPDSP)                += bswapdsp.o
>  OBJS-$(CONFIG_CABAC)                   += cabac.o
> -OBJS-$(CONFIG_CBS)                     += cbs.o
> +OBJS-$(CONFIG_CBS)                     += cbs.o cbs_bsf.o
>  OBJS-$(CONFIG_CBS_AV1)                 += cbs_av1.o
>  OBJS-$(CONFIG_CBS_H264)                += cbs_h2645.o cbs_sei.o h2645_parse.o
>  OBJS-$(CONFIG_CBS_H265)                += cbs_h2645.o cbs_sei.o h2645_parse.o
> diff --git a/libavcodec/cbs_bsf.c b/libavcodec/cbs_bsf.c
> new file mode 100644
> index 0000000000..429f360014
> --- /dev/null
> +++ b/libavcodec/cbs_bsf.c
> @@ -0,0 +1,161 @@
> +/*
> + * 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_internal.h"
> +#include "cbs_bsf.h"
> +
> +static int ff_cbs_bsf_update_side_data(AVBSFContext *bsf, AVPacket *pkt)

The ff_ prefix is not for static functions.

> +{
> +    CBSBSFContext           *ctx = bsf->priv_data;
> +    CodedBitstreamFragment *frag = &ctx->fragment;
> +    uint8_t *side_data;
> +    int side_data_size;
> +    int err;
> +
> +    side_data = av_packet_get_side_data(pkt, AV_PKT_DATA_NEW_EXTRADATA,
> +                                        &side_data_size);
> +    if (!side_data_size)
> +        return 0;
> +
> +    err = ff_cbs_read(ctx->input, frag, side_data, side_data_size);
> +    if (err < 0) {
> +        av_log(bsf, AV_LOG_ERROR,
> +               "Failed to read extradata from packet side data.\n");
> +        return err;
> +    }
> +
> +    err = ctx->type->update_fragment(bsf, NULL, frag);
> +    if (err < 0)
> +        goto fail;

This is inconsistent: All the other errors paths out of this function do
not reset the fragment; and that is fine, because the one and only
caller already does so. (Did you intend for this function to be more
standalone?)

> +
> +    err = ff_cbs_write_fragment_data(ctx->output, frag);
> +    if (err < 0) {
> +        av_log(bsf, AV_LOG_ERROR,
> +               "Failed to write extradata into packet side data.\n");
> +        return err;
> +    }
> +
> +    side_data = av_packet_new_side_data(pkt, AV_PKT_DATA_NEW_EXTRADATA,
> +                                        frag->data_size);
> +    if (!side_data)
> +        return AVERROR(ENOMEM);
> +    memcpy(side_data, frag->data, frag->data_size);
> +
> +    err = 0;
> +fail:
> +    ff_cbs_fragment_reset(frag);
> +    return err;
> +}
> +
> +int ff_cbs_bsf_filter(AVBSFContext *bsf, AVPacket *pkt)
> +{
> +    CBSBSFContext           *ctx = bsf->priv_data;
> +    CodedBitstreamFragment *frag = &ctx->fragment;
> +    int err;
> +
> +    err = ff_bsf_get_packet_ref(bsf, pkt);
> +    if (err < 0)
> +        return err;
> +
> +    err = ff_cbs_bsf_update_side_data(bsf, pkt);
> +    if (err < 0)
> +        goto fail;
> +
> +    err = ff_cbs_read_packet(ctx->input, frag, pkt);
> +    if (err < 0) {
> +        av_log(bsf, AV_LOG_ERROR, "Failed to read %s from packet.\n",
> +               ctx->type->fragment_name);
> +        goto fail;
> +    }
> +
> +    if (frag->nb_units == 0) {
> +        av_log(bsf, AV_LOG_ERROR, "No %s found in packet.\n",
> +               ctx->type->unit_name);
> +        err = AVERROR_INVALIDDATA;
> +        goto fail;
> +    }
> +
> +    err = ctx->type->update_fragment(bsf, pkt, frag);
> +    if (err < 0)
> +        goto fail;
> +
> +    err = ff_cbs_write_packet(ctx->output, pkt, frag);
> +    if (err < 0) {
> +        av_log(bsf, AV_LOG_ERROR, "Failed to write %s into packet.\n",
> +               ctx->type->fragment_name);
> +        goto fail;
> +    }
> +
> +    err = 0;
> +fail:
> +    ff_cbs_fragment_reset(frag);
> +
> +    if (err < 0)
> +        av_packet_unref(pkt);
> +
> +    return err;
> +}
> +
> +int ff_cbs_bsf_init(AVBSFContext *bsf, const CBSBSFType *type)
> +{
> +    CBSBSFContext           *ctx = bsf->priv_data;
> +    CodedBitstreamFragment *frag = &ctx->fragment;
> +    int err;
> +
> +    ctx->type = type;
> +
> +    err = ff_cbs_init(&ctx->input, type->codec_id, bsf);
> +    if (err < 0)
> +        return err;
> +
> +    err = ff_cbs_init(&ctx->output, type->codec_id, bsf);
> +    if (err < 0)
> +        return err;
> +
> +    if (bsf->par_in->extradata) {
> +        err = ff_cbs_read_extradata(ctx->input, frag, bsf->par_in);
> +        if (err < 0) {
> +            av_log(bsf, AV_LOG_ERROR, "Failed to read extradata.\n");
> +            goto fail;
> +        }
> +
> +        err = type->update_fragment(bsf, NULL, frag);
> +        if (err < 0)
> +            goto fail;
> +
> +        err = ff_cbs_write_extradata(ctx->output, bsf->par_out, frag);
> +        if (err < 0) {
> +            av_log(bsf, AV_LOG_ERROR, "Failed to write extradata.\n");
> +            goto fail;
> +        }
> +    }
> +
> +    err = 0;
> +fail:
> +    ff_cbs_fragment_reset(frag);
> +    return err;
> +}
> +
> +void ff_cbs_bsf_close(AVBSFContext *bsf)
> +{
> +    CBSBSFContext *ctx = bsf->priv_data;
> +
> +    ff_cbs_fragment_free(&ctx->fragment);
> +    ff_cbs_close(&ctx->input);
> +    ff_cbs_close(&ctx->output);
> +}
> diff --git a/libavcodec/cbs_bsf.h b/libavcodec/cbs_bsf.h
> new file mode 100644
> index 0000000000..8cab3f144c
> --- /dev/null
> +++ b/libavcodec/cbs_bsf.h
> @@ -0,0 +1,100 @@
> +/*
> + * 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_CBS_BSF_H
> +#define AVCODEC_CBS_BSF_H
> +
> +#include "cbs.h"
> +
> +
> +typedef struct CBSBSFType {
> +    enum AVCodecID codec_id;
> +
> +    // Name of a frame fragment in this codec (e.g. "access unit",
> +    // "temporal unit").
> +    const char *fragment_name;
> +
> +    // Name of a unit for this BSF, for use in error messages (e.g.
> +    // "NAL unit", "OBU").
> +    const char *unit_name;
> +
> +    // Update the content of a fragment with whatever metadata changes
> +    // are desired.  The associated AVPacket is provided so that any side
> +    // data associated with the fragment can be inspected or edited.  If
> +    // pkt is NULL, then an extradata header fragment is being updated.
> +    int (*update_fragment)(AVBSFContext *bsf, AVPacket *pkt,
> +                           CodedBitstreamFragment *frag);
> +} CBSBSFType;
> +
> +typedef struct CBSBSFContext {
> +    const AVClass         *class;
> +    const CBSBSFType      *type;
> +
> +    CodedBitstreamContext *input;
> +    CodedBitstreamContext *output;
> +    CodedBitstreamFragment fragment;
> +} CBSBSFContext;
> +
> +
> +int ff_cbs_bsf_filter(AVBSFContext *bsf, AVPacket *pkt);
> +int ff_cbs_bsf_init(AVBSFContext *bsf, const CBSBSFType *type);
> +void ff_cbs_bsf_close(AVBSFContext *bsf);
> +
> +
> +// Options for element manipulation.
> +enum {
> +    // Pass this element through unchanged.
> +    BSF_ELEMENT_PASS,
> +    // Insert this element, replacing any existing instances of it.
> +    // Associated values may be provided explicitly (as addtional options)
> +    // or implicitly (either as side data or deduced from other parts of
> +    // the stream).
> +    BSF_ELEMENT_INSERT,
> +    // Remove this element if it appears in the stream.
> +    BSF_ELEMENT_REMOVE,
> +    // Extract this element to side data, so that further manipulation
> +    // can happen elsewhere.
> +    BSF_ELEMENT_EXTRACT,
> +};
> +
> +#define BSF_ELEMENT_OPTIONS_PIR(name, help, field, unit_name) \
> +    { name, help, OFFSET(field), AV_OPT_TYPE_INT, \
> +        { .i64 = BSF_ELEMENT_PASS }, \
> +        BSF_ELEMENT_PASS, BSF_ELEMENT_REMOVE, FLAGS, unit_name }, \
> +    { "pass",   NULL, 0, AV_OPT_TYPE_CONST, \
> +        { .i64 = BSF_ELEMENT_PASS   }, .flags = FLAGS, .unit = unit_name }, \
> +    { "insert", NULL, 0, AV_OPT_TYPE_CONST, \
> +        { .i64 = BSF_ELEMENT_INSERT }, .flags = FLAGS, .unit = unit_name }, \
> +    { "remove", NULL, 0, AV_OPT_TYPE_CONST, \
> +        { .i64 = BSF_ELEMENT_REMOVE }, .flags = FLAGS, .unit = unit_name }
> +
> +#define BSF_ELEMENT_OPTIONS_PIRE(name, help, field, unit_name) \
> +    { name, help, OFFSET(field), AV_OPT_TYPE_INT, \
> +        { .i64 = BSF_ELEMENT_PASS }, \
> +        BSF_ELEMENT_PASS, BSF_ELEMENT_EXTRACT, FLAGS, unit_name }, \
> +    { "pass",   NULL, 0, AV_OPT_TYPE_CONST, \
> +        { .i64 = BSF_ELEMENT_PASS   }, .flags = FLAGS, .unit = unit_name }, \
> +    { "insert", NULL, 0, AV_OPT_TYPE_CONST, \
> +        { .i64 = BSF_ELEMENT_INSERT }, .flags = FLAGS, .unit = unit_name }, \
> +    { "remove", NULL, 0, AV_OPT_TYPE_CONST, \
> +        { .i64 = BSF_ELEMENT_REMOVE }, .flags = FLAGS, .unit = unit_name }, \
> +    { "extract", NULL, 0, AV_OPT_TYPE_CONST, \
> +        { .i64 = BSF_ELEMENT_EXTRACT }, .flags = FLAGS, .unit = unit_name } \
> +
> +
> +#endif /* AVCODEC_CBS_BSF_H */
> 



More information about the ffmpeg-devel mailing list