[FFmpeg-devel] [PATCH] libRIST: allow setting fifo size and fail on overflow.

[Marton Balint]

On Tue, 11 Jan 2022, Gijs Peskens wrote:

> Introduce fifo_size and overrun_nonfatal params to configure fifo buffer
> behavior.
>
> Use newly introduced RIST_DATA_FLAGS_OVERFLOW flag to check for overrun
> and error out in that case.
> ---
> doc/protocols.texi    |  9 +++++++++
> libavformat/librist.c | 37 +++++++++++++++++++++++++++++++++++++
> 2 files changed, 46 insertions(+)
>
> diff --git a/doc/protocols.texi b/doc/protocols.texi
> index d207df0b52..f1acf0cc77 100644
> --- a/doc/protocols.texi
> +++ b/doc/protocols.texi
> @@ -745,6 +745,15 @@ Set internal RIST buffer size in milliseconds for retransmission of data.
> Default value is 0 which means the librist default (1 sec). Maximum value is 30
> seconds.
>
> + at item fifo_size
> +Size of the librist receiver output fifo in number of packets. This must be a
> +power of 2.
> +Defaults to 8192 (vs the libRIST default of 1024).
> +
> + at item overrun_nonfatal=@var{1|0}
> +Survive in case of libRIST fifo buffer overrun. Default
> +value is 0.

Please use "librist" (all lowercase) consistently.

> +
> @item pkt_size
> Set maximum packet size for sending data. 1316 by default.
>
> diff --git a/libavformat/librist.c b/libavformat/librist.c
> index 378b635ea7..87c14eb265 100644
> --- a/libavformat/librist.c
> +++ b/libavformat/librist.c
> @@ -43,6 +43,9 @@
>     ((patch) + ((minor)* 0x100) + ((major) *0x10000))
> #define FF_LIBRIST_VERSION FF_LIBRIST_MAKE_VERSION(LIBRIST_API_VERSION_MAJOR, LIBRIST_API_VERSION_MINOR, LIBRIST_API_VERSION_PATCH)
> #define FF_LIBRIST_VERSION_41 FF_LIBRIST_MAKE_VERSION(4, 1, 0)
> +#define FF_LIBRIST_VERSION_42 FF_LIBRIST_MAKE_VERSION(4, 2, 0)
> +
> +#define FF_LIBRIST_FIFO_SIZE_DEFAULT 8192

FF_LIBRIST prefix is not really needed, as this is not in a header.

>
> typedef struct RISTContext {
>     const AVClass *class;
> @@ -52,6 +55,8 @@ typedef struct RISTContext {
>     int packet_size;
>     int log_level;
>     int encryption;
> +    int fifo_size;
> +    int overrun_nonfatal;
>     char *secret;
>
>     struct rist_logging_settings logging_settings;
> @@ -70,6 +75,8 @@ static const AVOption librist_options[] = {
>     { "main",        NULL,              0,                   AV_OPT_TYPE_CONST, {.i64=RIST_PROFILE_MAIN},     0, 0, .flags = D|E, "profile" },
>     { "advanced",    NULL,              0,                   AV_OPT_TYPE_CONST, {.i64=RIST_PROFILE_ADVANCED}, 0, 0, .flags = D|E, "profile" },
>     { "buffer_size", "set buffer_size in ms", OFFSET(buffer_size), AV_OPT_TYPE_INT, {.i64=0},                 0, 30000, .flags = D|E },
> +    { "fifo_size", "Set libRIST fifo buffer. Size must be power of 2", OFFSET(fifo_size), AV_OPT_TYPE_INT, {.i64=FF_LIBRIST_FIFO_SIZE_DEFAULT}, 2 << 9, 2 << 15, .flags = D|E },

Minimum and maximum binary notation is very strange. Use 1<<power, or 
maybe I'd just write 1024 and 65536. Much more readable. Are these 
arbitrary limits, or the implementation only supports these? Maybe you 
can be a bit more lax, e.g. 256 minimum and 262144 max.

> +    { "overrun_nonfatal", "survive in case of libRIST receiving circular buffer overrun", OFFSET(overrun_nonfatal), AV_OPT_TYPE_BOOL, {.i64 = 0}, 0, 1,    D },
>     { "pkt_size",    "set packet size", OFFSET(packet_size), AV_OPT_TYPE_INT,   {.i64=1316},                  1, MAX_PAYLOAD_SIZE,    .flags = D|E },
>     { "log_level",   "set loglevel",    OFFSET(log_level),   AV_OPT_TYPE_INT,   {.i64=RIST_LOG_INFO},        -1, INT_MAX, .flags = D|E },
>     { "secret", "set encryption secret",OFFSET(secret),      AV_OPT_TYPE_STRING,{.str=NULL},                  0, 0,       .flags = D|E },
> @@ -161,6 +168,20 @@ static int librist_open(URLContext *h, const char *uri, int flags)
>     if (ret < 0)
>         goto err;
>
> +    //Prior to 4.2.0 there was a bug in libRIST which made this call always fail.
> +#if FF_LIBRIST_VERSION >= FF_LIBRIST_VERSION_42
> +    if (flags & AVIO_FLAG_READ) {
> +        ret = rist_receiver_set_output_fifo_size(s->ctx, s->fifo_size);
> +        if (ret != 0) {
> +            goto err;
> +        }
> +    }
> +#else
> +    if (s->fifo_size != FF_LIBRIST_FIFO_SIZE_DEFAULT) {

Isn't this supposed to be if (s->fifo_size != 1024)? Considering that we 
are aiming for a bigger default in ffmpeg compared to what is in the 
library as default, maybe the user should be aware that we cannot set it?

> +        av_log(h, AV_LOG_ERROR, "libRIST prior to 0.2.7 has a bug which fails setting the fifo buffer size\n");
> +    }
> +#endif
> +

Thanks,
Marton