[FFmpeg-devel] [PATCH 1/2] ffmpeg_demux: init resume_warn variable

[FFmpeg-devel] [PATCH 1/2] ffmpeg_demux: init resume_warn variable

[Marvin Scholz]

Fixes an uninitialized read introduced with
6232f416b172358c9dd82462037953f02743df27

Fix CID1643162 Uninitialized scalar variable
---
 fftools/ffmpeg_demux.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fftools/ffmpeg_demux.c b/fftools/ffmpeg_demux.c
index cb4318c75b..6e01efc420 100644
--- a/fftools/ffmpeg_demux.c
+++ b/fftools/ffmpeg_demux.c
@@ -504,7 +504,7 @@ static void readrate_sleep(Demuxer *d)
                           (f->start_time != AV_NOPTS_VALUE ? f->start_time : 0)
                          );
     int64_t initial_burst = AV_TIME_BASE * d->readrate_initial_burst;
-    int resume_warn;
+    int resume_warn = 0;
 
     for (int i = 0; i < f->nb_streams; i++) {
         InputStream *ist = f->streams[i];
-- 
2.39.5 (Apple Git-154)

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[FFmpeg-devel] [RFC PATCH 2/2] ffmpeg_demux: make readrate stall warning input-specific

[Marvin Scholz]

Given the readrate catchup is input-specific, it seems to make sense to
also warn on a per-input demux basis.
---
 fftools/ffmpeg_demux.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/fftools/ffmpeg_demux.c b/fftools/ffmpeg_demux.c
index 6e01efc420..1f7ec20a43 100644
--- a/fftools/ffmpeg_demux.c
+++ b/fftools/ffmpeg_demux.c
@@ -101,6 +101,8 @@ typedef struct DemuxStream {
     int64_t                  resume_pts;
     // measure of how far behind packet reading is against spceified readrate
     int64_t                  lag;
+    // state for resume after stall warning
+    int                      resume_warned;
 } DemuxStream;
 
 typedef struct Demuxer {
@@ -504,7 +506,6 @@ static void readrate_sleep(Demuxer *d)
                           (f->start_time != AV_NOPTS_VALUE ? f->start_time : 0)
                          );
     int64_t initial_burst = AV_TIME_BASE * d->readrate_initial_burst;
-    int resume_warn = 0;
 
     for (int i = 0; i < f->nb_streams; i++) {
         InputStream *ist = f->streams[i];
@@ -523,12 +524,12 @@ static void readrate_sleep(Demuxer *d)
             ds->lag = lag;
             ds->resume_wc = now;
             ds->resume_pts = pts;
-            av_log_once(ds, AV_LOG_WARNING, AV_LOG_DEBUG, &resume_warn,
+            av_log_once(ds, AV_LOG_WARNING, AV_LOG_DEBUG, &ds->resume_warned,
                         "Resumed reading at pts %0.3f with rate %0.3f after a lag of %0.3fs\n",
                         (float)pts/AV_TIME_BASE, d->readrate_catchup, (float)lag/AV_TIME_BASE);
         }
         if (ds->lag && !lag)
-            ds->lag = ds->resume_wc = ds->resume_pts = 0;
+            ds->lag = ds->resume_wc = ds->resume_pts = ds->resume_warned = 0;
         if (ds->resume_wc) {
             elapsed = now - ds->resume_wc;
             limit_pts = ds->resume_pts + elapsed * d->readrate_catchup;
-- 
2.39.5 (Apple Git-154)

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Re: [FFmpeg-devel] [RFC PATCH 2/2] ffmpeg_demux: make readrate stall warning input-specific

[Gyan Doshi]

On 2025-04-23 02:26 am, Marvin Scholz wrote:
> Given the readrate catchup is input-specific, it seems to make sense to
> also warn on a per-input demux basis.

We want to warn once each time reading is resumed but only for the first 
stream resumption. That's the case right now.
With this change, if an input stalls thrice, only the resumption after 
the first stall will get reported.

Regards,
Gyan


> ---
>   fftools/ffmpeg_demux.c | 7 ++++---
>   1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/fftools/ffmpeg_demux.c b/fftools/ffmpeg_demux.c
> index 6e01efc420..1f7ec20a43 100644
> --- a/fftools/ffmpeg_demux.c
> +++ b/fftools/ffmpeg_demux.c
> @@ -101,6 +101,8 @@ typedef struct DemuxStream {
>       int64_t                  resume_pts;
>       // measure of how far behind packet reading is against spceified readrate
>       int64_t                  lag;
> +    // state for resume after stall warning
> +    int                      resume_warned;
>   } DemuxStream;
>   
>   typedef struct Demuxer {
> @@ -504,7 +506,6 @@ static void readrate_sleep(Demuxer *d)
>                             (f->start_time != AV_NOPTS_VALUE ? f->start_time : 0)
>                            );
>       int64_t initial_burst = AV_TIME_BASE * d->readrate_initial_burst;
> -    int resume_warn = 0;
>   
>       for (int i = 0; i < f->nb_streams; i++) {
>           InputStream *ist = f->streams[i];
> @@ -523,12 +524,12 @@ static void readrate_sleep(Demuxer *d)
>               ds->lag = lag;
>               ds->resume_wc = now;
>               ds->resume_pts = pts;
> -            av_log_once(ds, AV_LOG_WARNING, AV_LOG_DEBUG, &resume_warn,
> +            av_log_once(ds, AV_LOG_WARNING, AV_LOG_DEBUG, &ds->resume_warned,
>                           "Resumed reading at pts %0.3f with rate %0.3f after a lag of %0.3fs\n",
>                           (float)pts/AV_TIME_BASE, d->readrate_catchup, (float)lag/AV_TIME_BASE);
>           }
>           if (ds->lag && !lag)
> -            ds->lag = ds->resume_wc = ds->resume_pts = 0;
> +            ds->lag = ds->resume_wc = ds->resume_pts = ds->resume_warned = 0;
>           if (ds->resume_wc) {
>               elapsed = now - ds->resume_wc;
>               limit_pts = ds->resume_pts + elapsed * d->readrate_catchup;

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