On 25/02/2024 15:01, Marton Balint wrote:
On Sun, 25 Feb 2024, Mark Thompson wrote:
Since e0da916b8f5b079a4865eef7f64863f50785463d the ffmpeg utility has
held multiple frames output by the decoder in internal queues without
telling the decoder that it is going to do so. When the decoder has a
fixed-size pool of frames (common in some hardware APIs where the output
frames must be stored as an array texture) this could lead to the pool
being exhausted and the decoder getting stuck. Fix this by telling the
decoder to allocate additional frames according to the queue size.
[...]
diff --git a/fftools/ffmpeg_sched.h b/fftools/ffmpeg_sched.h
index 95f9c1d4db..315053ae42 100644
--- a/fftools/ffmpeg_sched.h
+++ b/fftools/ffmpeg_sched.h
@@ -233,6 +233,13 @@ int sch_add_filtergraph(Scheduler *sch, unsigned
nb_inputs, unsigned nb_outputs,
*/
int sch_add_mux(Scheduler *sch, SchThreadFunc func, int (*init)(void *),
void *ctx, int sdp_auto, unsigned thread_queue_size);
+
+/**
+ * Default size of a thread queue, used if thread_queue_size is not set on a
+ * call to sch_add_mux().
Not precisely, as this thread queue size is used for both frame queues and
packet queues.
Yes, it applies to both - hence the description I added not mentioning frames
or packets.
Historically the thread_queue_size option was introduced for packet queues for
demuxed packets, and recently on the output for muxing packets.
If we want to make the frame queue size adjustable as well, I think it should
be a separate option and maybe a separate constant should be added for its
default value.
This part is not changing anything about the queue sizes, it is just moving the
existing magic number hidden in queue_alloc() to a named constant.
I don't have any motivation to make the frame queue size adjustable; I added
the assert so that if someone wants to do that in future they know that they
need to take additional action to avoid breaking some decoders again.
+ */
+#define DEFAULT_THREAD_QUEUE_SIZE 8
Would you prefer that I make distinct DEFAULT_FRAME_THREAD_QUEUE_SIZE and
DEFAULT_PACKET_THREAD_QUEUE_SIZE (both 8?) and replace the magic number in
queue_alloc() with a selection between them based on the type? I have no
strong opinion on that, so I don't mind doing it if you would prefer it.
Thanks,
- Mark
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