如何在GStreamer中一起播放音頻和視頻？

Question

如何在GStreamer應用程序中一起播放音頻和視頻，但playbin / playbin2除外？

解復用后，如何在音頻接收器中播放音頻並在視頻接收器中播放視頻？

請回復。如果可能，請提供一個代碼示例。 提前致謝。

Answer 1

這是一個ogg文件的示例

gst-launch filesrc location=test.ogg ! oggdemux name=demuxer \  
    demuxer. ! queue ! vorbisdec ! audioconvert ! audioresample ! autoaudiosink \  
    demuxer. ! queue ! theoradec ! ffmpegcolorspace ! autovideosink

Answer 2

使用C語言對我來說效果很好：

//vdoAdoOGGPlayer.c

#include <gst/gst.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

typedef struct Queue {
    GstElement *queue[2];
} Queue;

void get_stream_type (char **result, char *file);
static gboolean bus_call (GstBus *bus, GstMessage *msg, gpointer data);
static void on_pad_added (GstElement *element, GstPad *pad, gpointer data);

int main (int argc, char *argv[])
{
    GMainLoop *loop;

    GstElement *pipeline, *source, *demuxer, *decoder, *conv, *sink;
    GstBus *bus;
    guint bus_watch_id;

    /* Check input arguments */
    if (argc != 2) {
        g_printerr ("Usage: %s <Ogg/Vorbis filename>\n", argv[0]);
        return -1;
    }

    /* Initialisation */
    gst_init (&argc, &argv);

    loop = g_main_loop_new (NULL, FALSE);

    /* Create gstreamer elements */
    pipeline = gst_pipeline_new ("audio-player");
    source   = gst_element_factory_make ("filesrc",       "file-source");
    demuxer  = gst_element_factory_make ("oggdemux",      "ogg-demuxer");

    /*視頻解析轉流輸出元素*/
    decoder  = gst_element_factory_make ("theoradec",     "vorbis-decoder"); 
    conv     = gst_element_factory_make ("videoconvert",  "converter");     
    sink     = gst_element_factory_make ("autovideosink", "video-output"); 

    /*音頻解析轉流輸出元素*/
    GstElement *decoder_audio = gst_element_factory_make ("vorbisdec", "audio-decoder");
    GstElement *converter_audio = gst_element_factory_make ("audioconvert", "audio_converter");
    GstElement *sink_audio = gst_element_factory_make ("autoaudiosink", "audio-ouput");

    if (!pipeline || !source || !demuxer || !decoder || !conv || !sink ) {
        g_printerr ("One element could not be created. Exiting.\n");
        return -1;
    }

    /* Set up the pipeline */

    g_object_set (G_OBJECT (source), "location", argv[1], NULL);

    GstElement *vdoQueue = NULL;
    GstElement *audioQueue = NULL;

    char format1[10] = { 0 };
    char format2[10] = { 0 };
    char *result[2];
    result[0] = format1;
    result[1] = format2;

    /*獲取包含的流編碼格式*/
    get_stream_type(result, argv[1]);

    /*如果包含theora編碼格式，則含有視頻流，進行相關元素的添加和鏈接*/
    if (strcmp (format1, "theora") == 0 || strcmp (format2, "theora") == 0)  {

        vdoQueue = gst_element_factory_make ("queue", "video-queue");
        gst_bin_add_many (GST_BIN(pipeline), vdoQueue, decoder, conv, sink , NULL);
        gst_element_link_many (vdoQueue, decoder, conv, sink, NULL);
    }

    if (strcmp (format1, "vorbis") == 0 || strcmp (format2, "vorbis") == 0) {

        audioQueue = gst_element_factory_make ("queue", "audio-queue");
        gst_bin_add_many (GST_BIN(pipeline), audioQueue, 
                decoder_audio, converter_audio, sink_audio, NULL);

        gst_element_link_many (audioQueue, decoder_audio, 
                converter_audio, sink_audio, NULL);
    }

    /* we add a message handler */
    bus = gst_pipeline_get_bus (GST_PIPELINE (pipeline));
    bus_watch_id = gst_bus_add_watch (bus, bus_call, loop);
    gst_object_unref (bus);

    gst_bin_add_many (GST_BIN (pipeline), source, demuxer,NULL);

    if ( gst_element_link (source, demuxer) != TRUE ){
        g_print("Elements couldn't be linked\n");
        return 1;
    }

    Queue queue;
    queue.queue[0] = audioQueue;
    queue.queue[1] = vdoQueue;

    g_signal_connect (demuxer, "pad-added", G_CALLBACK (on_pad_added), (void*)&queue);

    /* note that the demuxer will be linked to the decoder dynamically.
       The reason is that Ogg may contain various streams (for example
       audio and video). The source pad(s) will be created at run time,
       by the demuxer when it detects the amount and nature of streams.
       Therefore we connect a callback function which will be executed
       when the "pad-added" is emitted.*/

    /* Set the pipeline to "playing" state*/
    g_print ("Now playing: %s\n", argv[1]);
    gst_element_set_state (pipeline, GST_STATE_PLAYING);

    /* Iterate */
    g_print ("Running...\n");
    g_main_loop_run (loop);

    /* Out of the main loop, clean up nicely */
    g_print ("Returned, stopping playback\n");
    gst_element_set_state (pipeline, GST_STATE_NULL);

    g_print ("Deleting pipeline\n");
    gst_object_unref (GST_OBJECT (pipeline));
    g_source_remove (bus_watch_id);
    g_main_loop_unref (loop);

    return 0;
}

static void on_pad_added (GstElement *element, GstPad *pad, gpointer data)
{
    GstPad *sinkpad_audio, *sinkpad_vdo;
    Queue *queue = (Queue *) data;

    /* We can now link this pad with the vorbis-decoder sink pad */
    g_print ("Dynamic pad created, linking demuxer/decoder\n");

    /*queue元素值不為空則進行pad的連接*/
    if ( queue->queue[0] ) {
        sinkpad_audio = gst_element_get_static_pad (queue->queue[0], "sink");
        GstPad *pad1 = gst_element_get_compatible_pad (element, sinkpad_audio, NULL);
        if ( pad1 ) {
            gst_pad_link(pad1, sinkpad_audio);
            gst_object_unref (GST_OBJECT (pad1));
            g_print("link audio\n");
        }
        gst_object_unref (sinkpad_audio);
    }
    if ( queue->queue[1] ) {
        sinkpad_vdo = gst_element_get_static_pad (queue->queue[1], "sink");
        GstPad *pad2 = gst_element_get_compatible_pad (element, sinkpad_vdo, NULL);

        if ( pad2 ) {
            gst_pad_link(pad2, sinkpad_vdo);
            gst_object_unref (GST_OBJECT (pad2));
            g_print("link video\n");
        }
        gst_object_unref (sinkpad_vdo);
    }
}

void get_stream_type(char **result, char *file) {

    char buf[110];
    FILE *fp = fopen(file, "r");

    if ( !fp ) {
        fprintf(stderr, "Open file failed\n");
        exit(1);
    }

    if ( fread (buf, sizeof(char), sizeof(buf), fp) < 0) {

        fprintf (stderr, "fread failed\n");
        exit(1);
    }

    /*extract vorbis or theora format name if it's exist
     * and record its index*/
    int i1 = 0, i2 = 0;
    for ( int i=0; i<110; i++ ) {
        if (buf[i]=='t' || buf[i]=='v') {
            if ( !i1 )
                i1 = i;
            else
                i2 = i;
        }
    }

    buf[i1+6] = buf[i2+6] = '\0';
    strcpy(result[0], &buf[i1]);
    strcpy(result[1], &buf[i2]);

    result[0][6] = result[1][6] = '\0';

    printf("%s\n", result[0]);
    printf("%s\n", result[1]);

    fclose (fp);
}

static gboolean bus_call (GstBus *bus, GstMessage *msg, gpointer data)
{
    GMainLoop *loop = (GMainLoop *) data;

    switch (GST_MESSAGE_TYPE (msg)) {

        case GST_MESSAGE_EOS:
            g_print ("End of stream\n");
            g_main_loop_quit (loop);
            break;

        case GST_MESSAGE_ERROR: 
            {
                gchar  *debug;
                GError *error;
                gst_message_parse_error (msg, &error, &debug);
                g_free (debug);

                g_printerr ("Error: %s\n", error->message);
                g_error_free (error);

                g_main_loop_quit (loop);
                break;
            }
        default:
            break;
    }
    return TRUE;
}

用命令編譯：

gcc `pkg-config --cflags --libs gstreamer-1.0` vdoAdoOGGPlayer.c -g -o vdoAdoOGGPlayer

執行：

./vdoAdoOGGPlayer file.ogg

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