Use a GstTask with start/stop semantics for the decoder thread.

gst-libs/gst/vaapi/gstvaapidecoder.c

@@ -52,11 +52,8 @@ enum {
     PROP_CODEC_DATA
 };
 
-static gboolean
-gst_vaapi_decoder_start(GstVaapiDecoder *decoder);
-
-static gboolean
-gst_vaapi_decoder_stop(GstVaapiDecoder *decoder);
+/* Wait _at most_ 10 ms for encoded buffers between each decoding step */
+#define GST_VAAPI_DECODER_TIMEOUT (10000)
 
 static GstBuffer *
 pop_buffer(GstVaapiDecoder *decoder);
@@ -67,33 +64,31 @@ push_surface(GstVaapiDecoder *decoder, GstVaapiSurface *surface);
 static DecodedSurface *
 pop_surface(GstVaapiDecoder *decoder, GTimeVal *end_time);
 
-static gpointer
-decoder_thread_cb(gpointer data)
+static void
+decoder_task(gpointer data)
 {
-    GstVaapiDecoder * const decoder = data;
+    GstVaapiDecoder * const decoder = GST_VAAPI_DECODER_CAST(data);
     GstVaapiDecoderPrivate * const priv = decoder->priv;
     GstVaapiDecoderClass * const klass = GST_VAAPI_DECODER_GET_CLASS(decoder);
     GstBuffer *buffer;
 
-    g_object_ref(decoder);
-    while (!priv->decoder_thread_cancel) {
-        buffer = pop_buffer(decoder);
-        priv->decoder_status = klass->decode(decoder, buffer);
-        GST_DEBUG("decode frame (status = %d)", priv->decoder_status);
-        switch (priv->decoder_status) {
-        case GST_VAAPI_DECODER_STATUS_SUCCESS:
-        case GST_VAAPI_DECODER_STATUS_ERROR_NO_DATA:
-            break;
-        default:
-            /*  Send an empty surface to signal an error */
-            push_surface(decoder, NULL);
-            priv->decoder_thread_cancel = TRUE;
-            break;
-        }
-        gst_buffer_unref(buffer);
+    buffer = pop_buffer(decoder);
+    if (!buffer)
+        return;
+
+    priv->decoder_status = klass->decode(decoder, buffer);
+    GST_DEBUG("decode frame (status = %d)", priv->decoder_status);
+
+    switch (priv->decoder_status) {
+    case GST_VAAPI_DECODER_STATUS_SUCCESS:
+    case GST_VAAPI_DECODER_STATUS_ERROR_NO_DATA:
+        break;
+    default:
+        /*  Send an empty surface to signal an error */
+        push_surface(decoder, NULL);
+        gst_task_pause(priv->decoder_task);
+        break;
     }
-    g_object_unref(decoder);
-    return NULL;
 }
 
 static void
@@ -182,9 +177,6 @@ push_buffer(GstVaapiDecoder *decoder, GstBuffer *buffer)
     GST_DEBUG("queue encoded data buffer %p (%d bytes)",
               buffer, GST_BUFFER_SIZE(buffer));
 
-    if (!priv->decoder_thread && !gst_vaapi_decoder_start(decoder))
-        return FALSE;
-
     g_async_queue_push(priv->buffers, buffer);
     return TRUE;
 }
@@ -193,10 +185,15 @@ static GstBuffer *
 pop_buffer(GstVaapiDecoder *decoder)
 {
     GstVaapiDecoderPrivate * const priv = decoder->priv;
+    GTimeVal end_time;
     GstBuffer *buffer;
 
-    buffer = g_async_queue_pop(priv->buffers);
-    g_return_val_if_fail(buffer, NULL);
+    g_get_current_time(&end_time);
+    g_time_val_add(&end_time, GST_VAAPI_DECODER_TIMEOUT);
+
+    buffer = g_async_queue_timed_pop(priv->buffers, &end_time);
+    if (!buffer)
+        return NULL;
 
     GST_DEBUG("dequeue buffer %p for decoding (%d bytes)",
               buffer, GST_BUFFER_SIZE(buffer));
@@ -251,6 +248,9 @@ pop_surface(GstVaapiDecoder *decoder, GTimeVal *end_time)
 {
     GstVaapiDecoderPrivate * const priv = decoder->priv;
 
+    if (!gst_vaapi_decoder_start(decoder))
+        return NULL;
+
     return g_async_queue_timed_pop(priv->surfaces, end_time);
 }
 
@@ -423,8 +423,9 @@ gst_vaapi_decoder_init(GstVaapiDecoder *decoder)
     priv->surface_duration      = GST_CLOCK_TIME_NONE;
     priv->buffers               = g_async_queue_new();
     priv->surfaces              = g_async_queue_new();
-    priv->decoder_thread        = NULL;
-    priv->decoder_thread_cancel = FALSE;
+    priv->decoder_task          = NULL;
+
+    g_static_rec_mutex_init(&priv->decoder_task_lock);
 }
 
 /**
@@ -442,16 +443,15 @@ gst_vaapi_decoder_start(GstVaapiDecoder *decoder)
     /* This is an internal function */
     GstVaapiDecoderPrivate * const priv = decoder->priv;
 
-    if (!priv->decoder_thread) {
-        priv->decoder_thread = g_thread_create(
-            decoder_thread_cb, decoder,
-            TRUE,
-            NULL
-        );
-        if (!priv->decoder_thread)
-            return FALSE;
-    }
-    return TRUE;
+    if (priv->decoder_task)
+        return TRUE;
+
+    priv->decoder_task = gst_task_create(decoder_task, decoder);
+    if (!priv->decoder_task)
+        return FALSE;
+
+    gst_task_set_lock(priv->decoder_task, &priv->decoder_task_lock);
+    return gst_task_start(priv->decoder_task);
 }
 
 /**
@@ -470,14 +470,14 @@ gst_vaapi_decoder_stop(GstVaapiDecoder *decoder)
 {
     /* This is an internal function */
     GstVaapiDecoderPrivate * const priv = decoder->priv;
+    gboolean success;
 
-    if (priv->decoder_thread) {
-        push_buffer(decoder, NULL);
-        priv->decoder_thread_cancel = TRUE;
-        g_thread_join(priv->decoder_thread);
-        priv->decoder_thread = NULL;
-    }
-    return TRUE;
+    if (!priv->decoder_task)
+        return FALSE;
+
+    success = gst_task_join(priv->decoder_task);
+    priv->decoder_task = NULL;
+    return success;
 }
 
 /**

gst-libs/gst/vaapi/gstvaapidecoder.h

@@ -124,6 +124,12 @@ gst_vaapi_decoder_set_frame_rate(
     guint            den
 );
 
+gboolean
+gst_vaapi_decoder_start(GstVaapiDecoder *decoder);
+
+gboolean
+gst_vaapi_decoder_stop(GstVaapiDecoder *decoder);
+
 gboolean
 gst_vaapi_decoder_put_buffer_data(
     GstVaapiDecoder *decoder,

gst-libs/gst/vaapi/gstvaapidecoder_priv.h

@@ -22,7 +22,7 @@
 #define GST_VAAPI_DECODER_PRIV_H
 
 #include <glib.h>
-#include <gst/base/gstadapter.h>
+#include <gst/gsttask.h>
 #include <gst/vaapi/gstvaapidecoder.h>
 #include <gst/vaapi/gstvaapicontext.h>
 
@@ -97,9 +97,9 @@ struct _GstVaapiDecoderPrivate {
     GAsyncQueue                *surfaces;
     GstClockTime                surface_timestamp;
     GstClockTime                surface_duration;
-    GThread                    *decoder_thread;
+    GstTask                    *decoder_task;
+    GStaticRecMutex             decoder_task_lock;
     GstVaapiDecoderStatus       decoder_status;
-    guint                       decoder_thread_cancel   : 1;
 };
 
 gboolean