[FFmpeg-devel] [PATCH 2/2] libRIST: allow setting fifo size and fail on overflow.

[Marton Balint]

On Wed, 17 Nov 2021, Gijs Peskens wrote:

> Introduce fifo_size and overrun_nonfatal params to configure fifo buffer
> behavior.
> Fifo size is used to left shift 2, since libRIST only accepts powers of 2.

Can you please make fifo_size simply mean the number of packets? User 
facing options should be easily understandable by the user. Even if 
librist (at the moment) only supports power of two values.

>
> Use newly introduced RIST_DATA_FLAGS_OVERFLOW flag to check for overrun
> and error out in that case.
> ---
> libavformat/librist.c | 36 ++++++++++++++++++++++++++++++++++++
> 1 file changed, 36 insertions(+)
>
> diff --git a/libavformat/librist.c b/libavformat/librist.c
> index 378b635ea7..6f68868f3c 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_DEFAULT_SHIFT 13
>
> typedef struct RISTContext {
>     const AVClass *class;
> @@ -52,6 +55,8 @@ typedef struct RISTContext {
>     int packet_size;
>     int log_level;
>     int encryption;
> +    int fifo_shift;
> +    bool 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, applied as: buffer_size=2^fifo_size", OFFSET(fifo_shift), AV_OPT_TYPE_INT, {.i64=FF_LIBRIST_FIFO_DEFAULT_SHIFT}, 10, 63, .flags = D|E },
> +    { "overrun_nonfatal", "survive in case of libRIST receiving circular buffer overrun", OFFSET(overrun_nonfatal), AV_OPT_TYPE_BOOL, {.i64 = 0}, 0, 1,    D },

This changes existing default behaviour slightly by exiting in case of an 
overflow. I guess that it makes it consistent with udp.c, so fine with me 
if you think it is better that way.

>     { "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 +168,19 @@ 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, 2 << s->fifo_shift);
> +        if (ret != 0)
> +            goto err;
> +    }
> +#else
> +    if (s->fifo_buffer_size != FF_LIBRIST_FIFO_DEFAULT) {
> +        av_log(h, AV_LOG_ERROR, "libRIST prior to 0.2.7 has a bug which fails setting the fifo buffer size");
> +    }
> +#endif
> +
>     if (((s->encryption == 128 || s->encryption == 256) && !s->secret) ||
>         ((peer_config->key_size == 128 || peer_config->key_size == 256) && !peer_config->secret[0])) {
>         av_log(h, AV_LOG_ERROR, "secret is mandatory if encryption is enabled\n");
> @@ -223,8 +243,24 @@ static int librist_read(URLContext *h, uint8_t *buf, int size)
>         return AVERROR_EXTERNAL;
>     }
>
> +#if FF_LIBRIST_VERSION >= FF_LIBRIST_VERSION_42
> +    if (data_block->flags & RIST_DATA_FLAGS_OVERFLOW == RIST_DATA_FLAGS_OVERFLOW) {
> +        if (!s->overrun_nonfatal) {
> +            av_log(h, AV_LOG_ERROR, "Fifo buffer overrun. "
> +                    "To avoid, increase fifo_size URL option. "
> +                    "To survive in such case, use overrun_nonfatal option\n");
> +            size = AVERROR(EIO);
> +            goto out_free;
> +        } else {
> +            av_log(h, AV_LOG_WARNING, "Fifo buffer buffer overrun. "
> +                    "Surviving due to overrun_nonfatal option\n");
> +        }
> +    }
> +#endif
> +
>     size = data_block->payload_len;
>     memcpy(buf, data_block->payload, size);
> +out_free:
> #if FF_LIBRIST_VERSION < FF_LIBRIST_VERSION_41
>     rist_receiver_data_block_free((struct rist_data_block**)&data_block);
> #else
> -- 
> 2.32.0

doc/protocols.texi update is missing for the new options.

Thanks,
Marton