[FFmpeg-devel] [PATCH] lavf: add data: URI scheme.

Stefano Sabatini stefasab at gmail.com
Wed Dec 26 23:19:10 CET 2012


On date Wednesday 2012-12-26 22:49:37 +0100, Nicolas George encoded:
> 
> Signed-off-by: Nicolas George <nicolas.george at normalesup.org>
> ---
>  Changelog                |    1 +
>  doc/protocols.texi       |    8 ++++
>  libavformat/Makefile     |    1 +
>  libavformat/allformats.c |    1 +
>  libavformat/data_uri.c   |  114 ++++++++++++++++++++++++++++++++++++++++++++++
>  libavformat/version.h    |    4 +-
>  6 files changed, 127 insertions(+), 2 deletions(-)
>  create mode 100644 libavformat/data_uri.c
> 
> 
> Updated to suit Stefano's comments.
> 
> 
> diff --git a/Changelog b/Changelog
> index 9eec45c..7b408ef 100644
> --- a/Changelog
> +++ b/Changelog
> @@ -50,6 +50,7 @@ version <next>:
>  - documentation split into per-component manuals
>  - pp (postproc) filter ported from MPlayer
>  - NIST Sphere demuxer
> +- data: URI scheme
>  
>  
>  version 1.0:
> diff --git a/doc/protocols.texi b/doc/protocols.texi
> index e790459..702a3ea 100644
> --- a/doc/protocols.texi
> +++ b/doc/protocols.texi
> @@ -75,6 +75,14 @@ ffplay concat:split1.mpeg\|split2.mpeg\|split3.mpeg
>  Note that you may need to escape the character "|" which is special for
>  many shells.
>  
> + at section data
> +
> +Data in-line in the URI. See @url{http://en.wikipedia.org/wiki/Data_URI_scheme}.
> +

> + at example
> +ffmpeg -i "data:image/gif;base64,R0lGODdhCAAIAMIEAAAAAAAA//8AAP//AP///////////////ywAAAAACAAIAAADF0gEDLojDgdGiJdJqUX02iB4E8Q9jUMkADs=" smiley.png
> + at end example

Nit add an introductory sentence to the example, like:

For example, to convert a data uri with @command{ffmpeg}:

> +
>  @section file
>  
>  File access protocol.
> diff --git a/libavformat/Makefile b/libavformat/Makefile
> index 587fa42..2787a8a 100644
> --- a/libavformat/Makefile
> +++ b/libavformat/Makefile
> @@ -401,6 +401,7 @@ OBJS-$(CONFIG_BLURAY_PROTOCOL)           += bluray.o
>  OBJS-$(CONFIG_CACHE_PROTOCOL)            += cache.o
>  OBJS-$(CONFIG_CONCAT_PROTOCOL)           += concat.o
>  OBJS-$(CONFIG_CRYPTO_PROTOCOL)           += crypto.o
> +OBJS-$(CONFIG_DATA_PROTOCOL)             += data_uri.o
>  OBJS-$(CONFIG_FFRTMPCRYPT_PROTOCOL)      += rtmpcrypt.o rtmpdh.o
>  OBJS-$(CONFIG_FFRTMPHTTP_PROTOCOL)       += rtmphttp.o
>  OBJS-$(CONFIG_FILE_PROTOCOL)             += file.o
> diff --git a/libavformat/allformats.c b/libavformat/allformats.c
> index 6b4c27b..432e5b6 100644
> --- a/libavformat/allformats.c
> +++ b/libavformat/allformats.c
> @@ -288,6 +288,7 @@ void av_register_all(void)
>      REGISTER_PROTOCOL (CACHE, cache);
>      REGISTER_PROTOCOL (CONCAT, concat);
>      REGISTER_PROTOCOL (CRYPTO, crypto);
> +    REGISTER_PROTOCOL (DATA, data);
>      REGISTER_PROTOCOL (FFRTMPCRYPT, ffrtmpcrypt);
>      REGISTER_PROTOCOL (FFRTMPHTTP, ffrtmphttp);
>      REGISTER_PROTOCOL (FILE, file);
> diff --git a/libavformat/data_uri.c b/libavformat/data_uri.c
> new file mode 100644
> index 0000000..287514a
> --- /dev/null
> +++ b/libavformat/data_uri.c
> @@ -0,0 +1,114 @@
> +/*
> + * Copyright (c) 2012 Nicolas George
> + *
> + * 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 <string.h>
> +#include "libavutil/avstring.h"
> +#include "libavutil/base64.h"
> +#include "url.h"
> +
> +typedef struct {
> +    const uint8_t *data;
> +    void *tofree;
> +    size_t size;
> +    size_t pos;
> +} DataContext;
> +
> +static av_cold int data_open(URLContext *h, const char *uri, int flags)
> +{
> +    DataContext *dc = h->priv_data;
> +    const char *data, *opt, *next;
> +    char *ddata;
> +    int ret, base64 = 0;
> +    size_t in_size;
> +
> +    /* data:content/type[;base64],payload */
> +
> +    av_strstart(uri, "data:", &uri);
> +    data = strchr(uri, ',');

> +    if (!data) {
> +        av_log(h, AV_LOG_ERROR, "No ',' delimiter\n");

Nit: No ',' delimiter in uri '%s'

in order to provide some more context

> +        return AVERROR(EINVAL);
> +    }
> +    opt = uri;
> +    while (opt < data) {
> +        next = av_x_if_null(memchr(opt, ';', data - opt), data);
> +        if (opt == uri) {

> +            if (!memchr(opt, '/', next - opt)) /* basic validity check */
> +                return AVERROR(EINVAL);

missing error message

> +            av_log(h, AV_LOG_VERBOSE, "Content-type: %.*s\n",
> +                   (int)(next - opt), opt);
> +        } else {
> +            if (!av_strncasecmp(opt, "base64", next - opt)) {
> +                base64 = 1;
> +            } else {
> +                av_log(h, AV_LOG_VERBOSE, "Ignoring option '%.*s'\n",
> +                       (int)(next - opt), opt);
> +            }
> +        }
> +        opt = next + 1;
> +    }

I suspect the code could be made more simpler with some pattern
matching (sscanf).

> +
> +    data++;
> +    in_size = strlen(data);
> +    if (base64) {
> +        size_t out_size = 3 * in_size / 4 + 1;
> +
> +        if (out_size > INT_MAX || !(ddata = av_malloc(out_size)))
> +            return AVERROR(ENOMEM);

> +        if ((ret = av_base64_decode(ddata, data, out_size)) < 0) {

Maybe an error message here in the impossible case in which decode
fails.

> +            av_free(ddata);
> +            return ret;
> +        }
> +        dc->data = dc->tofree = ddata;
> +        dc->size = ret;
> +    } else {
> +        dc->data = data;
> +        dc->size = in_size;
> +    }
> +    return 0;
> +}
> +
> +static av_cold int data_close(URLContext *h)
> +{
> +    DataContext *dc = h->priv_data;
> +
> +    av_freep(&dc->tofree);
> +    return 0;
> +}
> +
> +static int data_read(URLContext *h, unsigned char *buf, int size)
> +{
> +    DataContext *dc = h->priv_data;
> +
> +    if (dc->pos >= dc->size)
> +        return AVERROR_EOF;
> +    size = FFMIN(size, dc->size - dc->pos);
> +    memcpy(buf, dc->data + dc->pos, size);
> +    dc->pos += size;
> +    return size;
> +}
> +
> +URLProtocol ff_data_protocol = {
> +    .name           = "data",
> +    .url_open       = data_open,
> +    .url_close      = data_close,
> +    .url_read       = data_read,
> +    .priv_data_size = sizeof(DataContext),
> +};
> diff --git a/libavformat/version.h b/libavformat/version.h
> index bd14e56..8a22dd4 100644
> --- a/libavformat/version.h
> +++ b/libavformat/version.h
> @@ -30,8 +30,8 @@
>  #include "libavutil/avutil.h"
>  
>  #define LIBAVFORMAT_VERSION_MAJOR 54
> -#define LIBAVFORMAT_VERSION_MINOR 50
> -#define LIBAVFORMAT_VERSION_MICRO 102
> +#define LIBAVFORMAT_VERSION_MINOR 51
> +#define LIBAVFORMAT_VERSION_MICRO 100
>  
>  #define LIBAVFORMAT_VERSION_INT AV_VERSION_INT(LIBAVFORMAT_VERSION_MAJOR, \
>                                                 LIBAVFORMAT_VERSION_MINOR, \

LGTM otherwise, thanks.
-- 
FFmpeg = Fiendish and Formidable Multipurpose Purposeless Eccentric Guru


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