[FFmpeg-devel] [PATCH] [RFC]doc/examples: alternative input handler

[Michael Niedermayer]

On Fri, Mar 30, 2018 at 02:47:25PM +0200, Bodecs Bela wrote:
> Hi All,
> 
> regularly, on different forums and mailing lists a requirement popups for a
> feature to automatically failover switching between main input and a
> secondary input in case of main input unavailability.
> 
> The base motivation: let's say you have a unreliable live stream source and
> you
> want to transcode its video and audio streams in realtime but you
> want to survive the ocasions when the source is unavailable. So use a
> secondary live source but the transition should occur seamlessly without
> breaking/re-starting the transcoding processs.
> 
> Some days ago there was a discussion on devel-irc about this topic and we
> concluded that this feature is not feasible inside ffmpeg without "hacking",
> but a separate client app could do this.
> 
> So I created this example app to handle two separate input sources and
> switching realtime between them. I am not sure wheter it should be inside
> the tools subdir.
> 
> The detailed description is available in the header section of the source
> file.
> 
> I will appretiate your suggestions about it.
> 
> Thank you in advance.
> 
> best,
> 
> Bela Bodecs
> 
> 

>  configure                        |    2 
>  doc/examples/Makefile            |    1 
>  doc/examples/Makefile.example    |    1 
>  doc/examples/alternative_input.c | 1233 +++++++++++++++++++++++++++++++++++++++

You may want to add yourself to MAINTAINERS, so it is not unmaintained
I think this is complex enough that it needs a maintainer


[...]

> +static int open_single_input(int input_index)
> +{
> +    int ret, i;
> +    AVInputFormat *input_format = NULL;
> +    AVDictionary * input_options = NULL;
> +    AVFormatContext * input_fmt_ctx = NULL;
> +
> +    if (app_ctx.input_format_names[input_index]) {
> +        if (!(input_format = av_find_input_format(app_ctx.input_format_names[input_index]))) {
> +            timed_log(AV_LOG_ERROR, "Input #%d Unknown input format: '%s'\n", input_index,
> +                      app_ctx.input_format_names[input_index]);
> +            return EINVAL;
> +        }
> +    }
> +
> +    av_dict_set(&input_options, "rw_timeout", "2000000", 0);
> +    av_dict_set(&input_options, "timeout", "2000", 0);

> +    if ((app_ctx.input_fmt_ctx[input_index] = avformat_alloc_context()) < 0)
> +            return AVERROR(ENOMEM);

i guess this was intended to be "!= NULL"

also you are mixing EINVAL with AVERROR(ENOMEM) these arent compatible. 
Either all should be AVERROR or none

thx

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

No great genius has ever existed without some touch of madness. -- Aristotle
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