x264enc and variable rate appsrc

Tue Sep 22 11:27:16 UTC 2020

Hi

What happens if you use a framerate of 0/1? This is the way to define a variable framerate.

Maybe the issue is with your decoder pipeline and the not the encoding. Have you tried setting 'sync=FALSE' for the video sink you're using?

________________________________
From: gstreamer-devel <gstreamer-devel-bounces at lists.freedesktop.org> on behalf of David J <davywj at gmail.com>
Sent: 22 September 2020 12:21
To: Discussion of the development of and with GStreamer
Subject: x264enc and variable rate appsrc

I have created a test pipeline (see code below) using a custom appsrc that creates an h264 stream and sends over rtp.

I am testing it with the following command line to receive and play the video stream:
gst-launch-1.0 -v udpsrc port=5000 caps = "application/x-rtp, media=(string)video, clock-rate=(int)90000, encoding-name=(string)H264, payload=(int)96" ! rtph264depay ! decodebin ! videoconvert ! autovideosink

The command-line inside the application looks like this:
appsrc name=MyAppSrc ! video/x-raw,width=640,height=360,framerate=10/1 ! videoconvert ! identity name=ident ! x264enc zerolatency=true speed-preset=superfast ! rtph264pay ! udpsink host=127.0.0.1 port=5000

At the moment the appsrc is generating frames at precisely 10fps and I set the buffer timestamps correctly. However, unless I also specify the framerate (in the caps string following the appsrc) as 10/1 the client viewer constantly complains of:
WARNING: from element /GstPipeline:pipeline0/GstAutoVideoSink:autovideosink0/GstD3D11VideoSinkBin:autovideosink0-actual-sink-d3d11video/GstD3D11VideoSink:d3d11videosink0: A lot of buffers are being dropped.
Additional debug info:
../libs/gst/base/gstbasesink.c(3134): gst_base_sink_is_too_late (): /GstPipeline:pipeline0/GstAutoVideoSink:autovideosink0/GstD3D11VideoSinkBin:autovideosink0-actual-sink-d3d11video/GstD3D11VideoSink:d3d11videosink0:
There may be a timestamping problem, or this computer is too slow.

The problem is:
In the real application, the appsrc will produce frames at a variable rate - between about 2 and 20 fps. How can I get this to work if I'm required to set a fixed framerate?

Provided the buffer timestamps are set, why does the framerate property have any bearing on the pipeine?

Here is the application code:

// NativeBasicPipeline.cpp : This file contains the 'main' function. Program execution begins and ends there.
//

#include <gst/gst.h>
#include <gst/app/gstappsrc.h>

GTimer* timer;

GstAppSrc* appSrc;

guint sourceid = 0;

int width = 1;

int colour = 255;

bool read_data()
{
    static GstClockTime time = 0;
    static guint64 offset = 0;

    GstFlowReturn ret;
    auto ms = g_timer_elapsed(timer, NULL);

    if (ms > 1.0 / 10.0) {
        auto size = 640 * 3 * 360;

        gpointer copy = g_malloc(size);

        memset(copy, colour % 255, size);

        colour += 10;

        GstBuffer* buffer = gst_buffer_new_wrapped(copy, size);

        //GST_BUFFER_TIMESTAMP(buffer) = pts;
        GST_BUFFER_PTS(buffer) = time;
        GST_BUFFER_DTS(buffer) = time;
        GST_BUFFER_DURATION(buffer) = 100 * GST_MSECOND;

        GST_BUFFER_OFFSET(buffer) = offset++;
        GST_BUFFER_OFFSET_END(buffer) = offset;

        time += 100 * GST_MSECOND;

        g_signal_emit_by_name(appSrc, "push-buffer", buffer, &ret);

        //ret = gst_app_src_push_buffer(appSrc, buffer);
        gst_buffer_unref(buffer);

        g_timer_start(timer);

        return TRUE;
    }

    return TRUE;
}

void start_feed(GstElement* pipeline, guint size, void* unused)
{
    if (sourceid == 0) {
        sourceid = g_idle_add((GSourceFunc)read_data, 0);
    }
}

void stop_feed(GstElement* pipeline, void* unused)
{
    if (sourceid != 0) {
        g_source_remove(sourceid);
        sourceid = 0;
    }
}

static gboolean print_field(GQuark field, const GValue* value, gpointer pfx) {
    gchar* str = gst_value_serialize(value);

    g_print("%s  %15s: %s\n", (gchar*)pfx, g_quark_to_string(field), str);
    g_free(str);
    return TRUE;
}

static void print_caps(const GstCaps* caps, const gchar* pfx) {
    guint i;

    g_return_if_fail(caps != NULL);

    if (gst_caps_is_any(caps)) {
        g_print("%sANY\n", pfx);
        return;
    }
    if (gst_caps_is_empty(caps)) {
        g_print("%sEMPTY\n", pfx);
        return;
    }

    for (i = 0; i < gst_caps_get_size(caps); i++) {
        GstStructure* structure = gst_caps_get_structure(caps, i);

        g_print("%s%s\n", pfx, gst_structure_get_name(structure));
        gst_structure_foreach(structure, print_field, (gpointer)pfx);
    }
}

void handoff(GstElement* pipeline, GstBuffer* buffer, void* unused)
{
    static int count = 0;
    static GstBuffer* buffers[50];

    //auto ident = gst_bin_get_by_name(GST_BIN(pipeline), "ident");
    auto pads = GST_ELEMENT_PADS(pipeline);

    auto pad0 = GST_PAD(pads->data);
    auto pad1 = GST_PAD(pads->next->data);

    auto caps = gst_pad_get_current_caps(pad1);

    print_caps(caps, "");

    if (count < 50)
    {
        GstBuffer* copy = gst_buffer_copy(buffer);

        buffers[count] = copy;

        ++count;
    }
    else
    {
        count = 100;

    }
}

int main()
{
    GstElement* pipeline;
    GstBus* bus;
    GstMessage* msg;

    timer = g_timer_new();

    /* Initialize GStreamer */
    gst_init(0, 0);

    /* Build the pipeline */

    GError* err = 0;

    //auto udpPipe = "videotestsrc pattern=smpte ! video/x-raw,width=640,height=360,framerate=10/1 ! videoscale ! videoconvert ! identity name=ident ! x264enc zerolatency=true speed-preset=superfast ! rtph264pay ! udpsink host=127.0.0.1 port=5000";

    //auto videoPipe = "videotestsrc pattern=smpte ! video/x-raw,width=640,height=360,framerate=10/1 ! videoscale ! videoconvert ! autovideosink";

    auto appSrcPipe = "appsrc name=MyAppSrc ! video/x-raw,width=640,height=360 ! videoconvert ! identity name=ident ! x264enc zerolatency=true speed-preset=superfast ! rtph264pay ! udpsink host=127.0.0.1 port=5000";

    //auto appSrcPipeVideo = "appsrc name=MyAppSrc ! videoscale ! videoconvert ! autovideosink";

    pipeline =
        gst_parse_launch
        (appSrcPipe,
            &err);

    appSrc = (GstAppSrc*)gst_bin_get_by_name(GST_BIN(pipeline), "MyAppSrc");

    g_object_set(G_OBJECT(appSrc), "format", GST_FORMAT_TIME, NULL);

    g_signal_connect(appSrc, "need-data", G_CALLBACK(start_feed), 0);
    g_signal_connect(appSrc, "enough-data", G_CALLBACK(stop_feed), 0);

    auto caps = gst_caps_new_simple("video/x-raw",
        "format", G_TYPE_STRING, "RGB",
        "bpp", G_TYPE_INT, 24,
        "depth", G_TYPE_INT, 24,
        "width", G_TYPE_INT, 640,
        "height", G_TYPE_INT, 360,
        NULL);

    gst_app_src_set_caps((GstAppSrc*)appSrc, caps);

    //GstPad* pad = gst_element_get_static_pad(appSrc, "src");

    //auto ident = gst_bin_get_by_name(GST_BIN(pipeline), "ident");

    //g_signal_connect(ident, "handoff", G_CALLBACK(handoff), 0);

    /* Start playing */
    gst_element_set_state(pipeline, GST_STATE_PLAYING);

    auto main_loop = g_main_loop_new(NULL, FALSE);
    g_main_loop_run(main_loop);

    /* Wait until error or EOS */
    bus = gst_element_get_bus(pipeline);
    msg =
        gst_bus_timed_pop_filtered(bus, GST_CLOCK_TIME_NONE,
            (GstMessageType)(GST_MESSAGE_ERROR | GST_MESSAGE_EOS));

    /* Free resources */
    if (msg != NULL)
        gst_message_unref(msg);
    gst_object_unref(bus);
    gst_element_set_state(pipeline, GST_STATE_NULL);
    gst_object_unref(pipeline);
    return 0;
}

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