[FFmpeg-devel] [PATCH 1/1] libavdevice/decklink: configurablity to set max queue size

[Marton Balint]

On Mon, 14 Aug 2017, Patagar, Ravindra wrote:

>
> Configurablity to set max queue size so that worst case latency can be controlled.
> Signed-off-by: Ravindra Patagar <rpatagar at akamai.com>
> ---
> libavdevice/decklink_common.h   | 2 ++
> libavdevice/decklink_common_c.h | 2 ++
> libavdevice/decklink_dec.cpp    | 7 +++++--
> libavdevice/decklink_dec_c.c    | 2 ++
> 4 files changed, 11 insertions(+), 2 deletions(-)
>
> diff --git a/libavdevice/decklink_common.h b/libavdevice/decklink_common.h
> index c12cf18..64cc722 100644
> --- a/libavdevice/decklink_common.h
> +++ b/libavdevice/decklink_common.h
> @@ -1,6 +1,7 @@
> /*
>  * Blackmagic DeckLink common code
>  * Copyright (c) 2013-2014 Ramiro Polla, Luca Barbato, Deti Fliegl
> + * Copyright (c) 2017 Akamai Technologies, Inc.
>  *
>  * This file is part of FFmpeg.
>  *
> @@ -38,6 +39,7 @@ typedef struct AVPacketQueue {
>     pthread_mutex_t mutex;
>     pthread_cond_t cond;
>     AVFormatContext *avctx;
> +    int max_q_size;
> } AVPacketQueue;
>
> struct decklink_ctx {
> diff --git a/libavdevice/decklink_common_c.h b/libavdevice/decklink_common_c.h
> index 72c5f9a..0ddd32a 100644
> --- a/libavdevice/decklink_common_c.h
> +++ b/libavdevice/decklink_common_c.h
> @@ -1,6 +1,7 @@
> /*
>  * Blackmagic DeckLink common code
>  * Copyright (c) 2013-2014 Ramiro Polla
> + * Copyright (c) 2017 Akamai Technologies, Inc.
>  *
>  * This file is part of FFmpeg.
>  *
> @@ -48,6 +49,7 @@ struct decklink_cctx {
>     int video_input;
>     int draw_bars;
>     char *format_code;
> +    int queue_size;
> };
>
> #endif /* AVDEVICE_DECKLINK_COMMON_C_H */
> diff --git a/libavdevice/decklink_dec.cpp b/libavdevice/decklink_dec.cpp
> index 72449a8..8e85c65 100644
> --- a/libavdevice/decklink_dec.cpp
> +++ b/libavdevice/decklink_dec.cpp
> @@ -1,6 +1,7 @@
> /*
>  * Blackmagic DeckLink input
>  * Copyright (c) 2013-2014 Luca Barbato, Deti Fliegl
> + * Copyright (c) 2017 Akamai Technologies, Inc.
>  *
>  * This file is part of FFmpeg.
>  *
> @@ -187,10 +188,12 @@ static uint8_t* teletext_data_unit_from_vanc_data(uint8_t *src, uint8_t *tgt, in
>
> static void avpacket_queue_init(AVFormatContext *avctx, AVPacketQueue *q)
> {
> +    struct decklink_cctx * ctx = (struct decklink_cctx *)avctx->priv_data;
>     memset(q, 0, sizeof(AVPacketQueue));
>     pthread_mutex_init(&q->mutex, NULL);
>     pthread_cond_init(&q->cond, NULL);
>     q->avctx = avctx;
> +    q->max_q_size = ctx->queue_size;
> }
>
> static void avpacket_queue_flush(AVPacketQueue *q)
> @@ -230,8 +233,8 @@ static int avpacket_queue_put(AVPacketQueue *q, AVPacket *pkt)
> {
>     AVPacketList *pkt1;
>
> -    // Drop Packet if queue size is > 1GB
> -    if (avpacket_queue_size(q) >  1024 * 1024 * 1024 ) {
> +    // Drop Packet if queue size is > maximum queue size
> +    if (avpacket_queue_size(q) >  q->max_q_size ) {
>         av_log(q->avctx, AV_LOG_WARNING,  "Decklink input buffer overrun!\n");
>         return -1;
>     }
> diff --git a/libavdevice/decklink_dec_c.c b/libavdevice/decklink_dec_c.c
> index 5b26d12..ea828be 100644
> --- a/libavdevice/decklink_dec_c.c
> +++ b/libavdevice/decklink_dec_c.c
> @@ -1,6 +1,7 @@
> /*
>  * Blackmagic DeckLink input
>  * Copyright (c) 2014 Deti Fliegl
> + * Copyright (c) 2017 Akamai Technologies, Inc.
>  *
>  * This file is part of FFmpeg.
>  *
> @@ -64,6 +65,7 @@ static const AVOption options[] = {
>     { "reference",     NULL,                                          0,  AV_OPT_TYPE_CONST, { .i64 = PTS_SRC_REFERENCE}, 0, 0, DEC, "pts_source"},
>     { "wallclock",     NULL,                                          0,  AV_OPT_TYPE_CONST, { .i64 = PTS_SRC_WALLCLOCK}, 0, 0, DEC, "pts_source"},
>     { "draw_bars",     "draw bars on signal loss" , OFFSET(draw_bars),    AV_OPT_TYPE_BOOL,  { .i64 = 1}, 0, 1, DEC },
> +    { "qbufsize",      "Input queue buffer size",   OFFSET(queue_size),    AV_OPT_TYPE_INT,   { .i64 = (1024 * 1024 * 1024)}, 0, INT_MAX, DEC, "bytes"},

I'd rather call the option "queue_size", shortened names should be fine 
for variables, but for option names we tend to use normal text.

Also please add documentation for it and increase libavdevice micro 
version.

Thanks,
Marton