[FFmpeg-devel] libavformat/tee: Add fifo support for tee

From: Jan Sebechlebsky <sebechlebskyjan@gmail.com>

Signed-off-by: Jan Sebechlebsky <sebechlebskyjan@gmail.com>
---
This commit makes use of fifo muxer together with tee muxer
easier, fifo muxer does not have to be explicitly specified
for each slave. For the most simple use case it is sufficient
to turn fifo muxer on for all slaves by switching on use_fifo
option. Same options can be passed to all fifo muxer instances of
slaves by assigning them to fifo_options of tee. 
Both use_fifo option and individual fifo_options can be 
overriden per slave if needed.

 doc/muxers.texi   | 20 +++++++++++++
 libavformat/tee.c | 89 ++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 108 insertions(+), 1 deletion(-)

On Fri, Oct 07, 2016 at 01:03:03AM +0200, sebechlebskyjan@gmail.com wrote:
> From: Jan Sebechlebsky <sebechlebskyjan@gmail.com>
> 
> Signed-off-by: Jan Sebechlebsky <sebechlebskyjan@gmail.com>
> ---
> This commit makes use of fifo muxer together with tee muxer
> easier, fifo muxer does not have to be explicitly specified
> for each slave. For the most simple use case it is sufficient
> to turn fifo muxer on for all slaves by switching on use_fifo
> option. Same options can be passed to all fifo muxer instances of
> slaves by assigning them to fifo_options of tee. 
> Both use_fifo option and individual fifo_options can be 
> overriden per slave if needed.
> 
>  doc/muxers.texi   | 20 +++++++++++++
>  libavformat/tee.c | 89 ++++++++++++++++++++++++++++++++++++++++++++++++++++++-
>  2 files changed, 108 insertions(+), 1 deletion(-)
> 
> diff --git a/doc/muxers.texi b/doc/muxers.texi
> index 9ec2e31..b88b83c 100644
> --- a/doc/muxers.texi
> +++ b/doc/muxers.texi
> @@ -1473,6 +1473,7 @@ Specify whether to remove all fragments when finished. Default 0 (do not remove)
>  
>  @end table
>  
> +@anchor{fifo}
>  @section fifo
>  
>  The fifo pseudo-muxer allows the separation of encoding and muxing by using
> @@ -1580,6 +1581,18 @@ with the tee muxer; encoding can be a very expensive process. It is not
>  useful when using the libavformat API directly because it is then possible
>  to feed the same packets to several muxers directly.
>  
> +@table @option
> +
> +@item use_fifo @var{bool}
> +If set to 1, slave outputs will be processed in separate thread using @ref{fifo}
> +muxer. This allows to compensate for different speed/latency/reliability of
> +outputs and setup transparent recovery. By default this feature is turned off.
> +
> +@item fifo_options
> +Options to pass to fifo pseudo-muxer instances. See @ref{fifo}.
> +
> +@end table
> +
>  The slave outputs are specified in the file name given to the muxer,
>  separated by '|'. If any of the slave name contains the '|' separator,
>  leading or trailing spaces or any special character, it must be
> @@ -1601,6 +1614,13 @@ output name suffix.
>  Specify a list of bitstream filters to apply to the specified
>  output.
>  
> +@item use_fifo @var{bool}
> +This allows to override tee muxer use_fifo option for individual slave muxer.
> +
> +@item fifo_options
> +This allows to override tee muxer fifo_options for individual slave muxer.
> +See @ref{fifo}.
> +
>  It is possible to specify to which streams a given bitstream filter
>  applies, by appending a stream specifier to the option separated by
>  @code{/}. @var{spec} must be a stream specifier (see @ref{Format
> diff --git a/libavformat/tee.c b/libavformat/tee.c
> index d59ad4d..764135d 100644
> --- a/libavformat/tee.c
> +++ b/libavformat/tee.c
> @@ -40,6 +40,8 @@ typedef struct {
>      AVBSFContext **bsfs; ///< bitstream filters per stream
>  
>      SlaveFailurePolicy on_fail;
> +    int use_fifo;
> +    AVDictionary *fifo_options;
>  
>      /** map from input to output streams indexes,
>       * disabled output streams are set to -1 */
> @@ -52,15 +54,28 @@ typedef struct TeeContext {
>      unsigned nb_slaves;
>      unsigned nb_alive;
>      TeeSlave *slaves;
> +    int use_fifo;
> +    AVDictionary *fifo_options;
> +    char *fifo_options_str;
>  } TeeContext;
>  
>  static const char *const slave_delim     = "|";
>  static const char *const slave_bsfs_spec_sep = "/";
>  static const char *const slave_select_sep = ",";
>  
> +#define OFFSET(x) offsetof(TeeContext, x)
> +static const AVOption options[] = {
> +        {"use_fifo", "Use fifo pseudo-muxer to separate actual muxers from encoder",
> +         OFFSET(use_fifo), AV_OPT_TYPE_BOOL, {.i64 = 0}, 0, 1, AV_OPT_FLAG_ENCODING_PARAM},
> +        {"fifo_options", "fifo pseudo-muxer options", OFFSET(fifo_options_str),
> +         AV_OPT_TYPE_STRING, {.str = NULL}, 0, 0, AV_OPT_FLAG_ENCODING_PARAM},
> +        {NULL}
> +};
> +
>  static const AVClass tee_muxer_class = {
>      .class_name = "Tee muxer",
>      .item_name  = av_default_item_name,
> +    .option = options,
>      .version    = LIBAVUTIL_VERSION_INT,
>  };
>  
> @@ -81,6 +96,27 @@ static inline int parse_slave_failure_policy_option(const char *opt, TeeSlave *t
>      return AVERROR(EINVAL);
>  }
>  
> +static int parse_slave_fifo_options(const char * use_fifo,
> +                                    const char * fifo_options, TeeSlave * tee_slave)
> +{
> +    int ret = 0;
> +
> +    if (use_fifo) {
> +        if (av_match_name(use_fifo, "true,y,yes,enable,enabled,on,1")) {
> +            tee_slave->use_fifo = 1;
> +        } else if (av_match_name(use_fifo, "false,n,no,disable,disabled,off,0")) {
> +            tee_slave->use_fifo = 0;
> +        } else {
> +            return AVERROR(EINVAL);
> +        }
> +    }
> +
> +    if (fifo_options)
> +        ret = av_dict_parse_string(&tee_slave->fifo_options, fifo_options, "=", ":", 0);
> +
> +    return ret;
> +}
> +
>  static int close_slave(TeeSlave *tee_slave)
>  {
>      AVFormatContext *avf;
> @@ -125,6 +161,7 @@ static int open_slave(AVFormatContext *avf, char *slave, TeeSlave *tee_slave)
>      AVDictionaryEntry *entry;
>      char *filename;
>      char *format = NULL, *select = NULL, *on_fail = NULL;
> +    char *use_fifo = NULL, *fifo_options_str = NULL;
>      AVFormatContext *avf2 = NULL;
>      AVStream *st, *st2;
>      int stream_count;
> @@ -145,6 +182,8 @@ static int open_slave(AVFormatContext *avf, char *slave, TeeSlave *tee_slave)
>      STEAL_OPTION("f", format);
>      STEAL_OPTION("select", select);
>      STEAL_OPTION("onfail", on_fail);
> +    STEAL_OPTION("use_fifo", use_fifo);
> +    STEAL_OPTION("fifo_options", fifo_options_str);
>  
>      ret = parse_slave_failure_policy_option(on_fail, tee_slave);
>      if (ret < 0) {
> @@ -153,7 +192,43 @@ static int open_slave(AVFormatContext *avf, char *slave, TeeSlave *tee_slave)
>          goto end;
>      }
>  
> -    ret = avformat_alloc_output_context2(&avf2, NULL, format, filename);
> +    ret = parse_slave_fifo_options( use_fifo, fifo_options_str, tee_slave);
> +    if (ret < 0) {
> +        av_log(avf, AV_LOG_ERROR, "Error parsing fifo options: %s\n", av_err2str(ret));
> +        goto end;
> +    }
> +
> +    if (tee_slave->use_fifo) {
> +
> +        if (options) {
> +            char *format_options_str = NULL;
> +            ret = av_dict_get_string(options, &format_options_str, '=', ':');
> +            if (ret < 0)
> +                goto end;
> +
> +            ret = av_dict_set(&tee_slave->fifo_options, "format_options", format_options_str,
> +                              AV_DICT_DONT_STRDUP_VAL);
> +            if (ret < 0) {
> +                av_free(format_options_str);

double free i think


> +                goto end;
> +            }
> +        }
> +
> +        if (format) {
> +            ret = av_dict_set(&tee_slave->fifo_options, "fifo_format", format,
> +                              AV_DICT_DONT_STRDUP_VAL);
> +            if (ret < 0)
> +                goto end;

here too

see: av_dist_set() doxy
 * Note: If AV_DICT_DONT_STRDUP_KEY or AV_DICT_DONT_STRDUP_VAL is set,
 * these arguments will be freed on error.
 
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