问题
I am change an app over to WPF, it plays audio and video and pictures all based on timed events .. I used "string MciCommand = string.Format("play frames FROM {0} to {1} {2}"" , before.
I have been searching and trying to fix this problem now in WPF c#
- I have a video (wmv) and I have multiple sections that need to be played together. example .. section1 start(200ms) stop(250ms) section2 start(5000ms) stop(15000ms)
- finally I need it to pause on a a still frame ..
I have tried using a timer, and a empty while loop and it doesn't seek properly. I am at a loss media element doesn't seem to support this type of use. I thought about wpfmediakit and direct show is very hard to wrap my novice wpf skills around.
any help would be greatly appreciated...
回答1:
this was how I ended up solving my problem .. I used a list of properties and used it like a script that I loop through . and if the position in larger than the end time. it trigger the timer and goes to the next item in the list .. there is still some things that could be made a bit more refined .. like the textbox4 changed event also triggers next_item but it gets the job done .. for now .. Hopefully this helps someone with the same issue ...
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using System.Windows.Media.Animation;
using System.ComponentModel;
using System.Threading;
namespace WpfApplication6
{
public partial class MainWindow : Window
{
BackgroundWorker position = new BackgroundWorker();
BackgroundWorker test_position = new BackgroundWorker();
public List<video_script> script_list = new List<video_script>();
int scrip_index;
public class video_script
{
public string action { get; set; }
public TimeSpan start_time { get; set; }
public TimeSpan endtime { get; set; }
public string filename { get; set; }
}
private void position_DoWork(object sender, DoWorkEventArgs e)
{
Thread.Sleep(100);
}
private void position_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
if (mediaElement1.Position > TimeSpan.FromMilliseconds(Convert.ToInt32(tb_endtime.Text)))
{
next_item();
}
else position.RunWorkerAsync();
textBox4.Text = "Play";
textBox3.Text = mediaElement1.Position.ToString();
}
public MainWindow()
{
InitializeComponent();
position.DoWork += new DoWorkEventHandler(position_DoWork);
position.RunWorkerCompleted += new RunWorkerCompletedEventHandler(position_RunWorkerCompleted);
position.WorkerSupportsCancellation = true;
test_position.DoWork += new DoWorkEventHandler(test_position_DoWork);
test_position.RunWorkerCompleted += new RunWorkerCompletedEventHandler(test_position_RunWorkerCompleted);
test_position.WorkerSupportsCancellation = true;
}
private void Mediasource_Click(object sender, RoutedEventArgs e)
{
if (!position.IsBusy) position.RunWorkerAsync();
mediaElement1.Source = new Uri(tb_filename.Text);
mediaElement1.LoadedBehavior = System.Windows.Controls.MediaState.Manual;
mediaElement1.UnloadedBehavior = System.Windows.Controls.MediaState.Manual;
mediaElement1.ScrubbingEnabled = true;
mediaElement1.Play();
}
private void stopbutton_Click(object sender, RoutedEventArgs e)
{
mediaElement1.Stop();
}
private void Playbutton_Click(object sender, RoutedEventArgs e)
{
scrip_index = 0;
mediaElement1.Play();
mediaElement1.LoadedBehavior = System.Windows.Controls.MediaState.Manual;
mediaElement1.UnloadedBehavior = System.Windows.Controls.MediaState.Manual;
mediaElement1.ScrubbingEnabled = true;
}
private void pausebutton_Click(object sender, RoutedEventArgs e)
{
if (mediaElement1.CanPause)
{
mediaElement1.Pause();
}
}
private void AddToListbutton_Click(object sender, RoutedEventArgs e)
{
video_script temp_item = new video_script();
temp_item.filename = tb_filename.Text;
temp_item.start_time = TimeSpan.FromMilliseconds(Convert.ToInt32(tb_starttime.Text));
temp_item.endtime = TimeSpan.FromMilliseconds(Convert.ToInt32(tb_endtime.Text));
temp_item.action = tb_action.Text;
script_list.Add(temp_item);
listBox1.Items.Add(temp_item.filename + " | " + tb_starttime.Text + " | " + tb_endtime.Text + " | " + tb_action.Text);
}
private void positionbox_TextChanged(object sender, TextChangedEventArgs e)
{
if (script_list.Count != 0)
{
if (script_list[scrip_index].endtime < mediaElement1.Position) next_item();
}
}
#region test button area
private void next_item()
{
if (scrip_index < script_list.Count() - 1)
{
scrip_index++;
switch (script_list[scrip_index].action)
{
case "Load":
mediaElement1.LoadedBehavior = System.Windows.Controls.MediaState.Manual;
mediaElement1.UnloadedBehavior = System.Windows.Controls.MediaState.Manual;
if (mediaElement1.Source != new Uri(script_list[scrip_index].filename)) mediaElement1.Source = new Uri(script_list[scrip_index].filename);
mediaElement1.ScrubbingEnabled = true;
playing = false;
next_item();
break;
case "Play":
mediaElement1.Play();
playing = true;
if(!test_position.IsBusy) test_position.RunWorkerAsync();
break;
case "Pause":
mediaElement1.Pause();
playing = false;
break;
case "Seek":
mediaElement1.Position = script_list[scrip_index].start_time;
playing = true;
break;
case "Stop":
mediaElement1.Stop();
playing = false;
break;
}
}
}
private void test_position_DoWork(object sender, DoWorkEventArgs e)
{
Thread.Sleep(100);
}
private void test_position_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
if (mediaElement1.Position > script_list[scrip_index].endtime )
{
next_item();
}
else test_position.RunWorkerAsync();
textBox4.Text = "Play";
textBox3.Text = mediaElement1.Position.ToString();
if (playing && !test_position.IsBusy) test_position.RunWorkerAsync();
}
private void testbutton_Click(object sender, RoutedEventArgs e)
{
if (mediaElement1.Source != new Uri(tb_filename.Text)) mediaElement1.Source = new Uri(tb_filename.Text);
mediaElement1.LoadedBehavior = System.Windows.Controls.MediaState.Manual;
mediaElement1.UnloadedBehavior = System.Windows.Controls.MediaState.Manual;
mediaElement1.Play();
mediaElement1.ScrubbingEnabled = true;
mediaElement1.Position = TimeSpan.FromMilliseconds(Convert.ToInt32(tb_starttime.Text));
if (test_position.IsBusy) test_position.CancelAsync();
if (!test_position.IsBusy) test_position.RunWorkerAsync();
}
bool playing;
#endregion
#region slider region
private void slider1_ValueChanged(object sender, RoutedPropertyChangedEventArgs<double> e)
{
if (slider1.Value > slider2.Value) slider2.Value = slider1.Value - 1;
}
private void slidermax_values_TextChanged(object sender, TextChangedEventArgs e)
{
slider1.Maximum = Convert.ToInt32(tb_slider_maxvalue.Text);
slider2.Maximum = Convert.ToInt32(tb_slider_maxvalue.Text);
}
private void slider2_ValueChanged(object sender, RoutedPropertyChangedEventArgs<double> e)
{
if (slider2.Value < slider1.Value) slider1.Value = slider2.Value - 1;
}
#endregion
private void start_script_Click(object sender, RoutedEventArgs e)
{
scrip_index = -1;
next_item();
}
private void mediaElement1_MediaOpened(object sender, RoutedEventArgs e)
{
}
}
}
here is the Xaml for the form that I used for testing....
<Window x:Class="WpfApplication6.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="402" Width="922" WindowStyle="ThreeDBorderWindow">
<Grid>
<Button Content="mediasource load" Height="23" HorizontalAlignment="Left" Margin="10,10,0,0" Name="button1" VerticalAlignment="Top" Width="75" Click="Mediasource_Click" />
<Button Content="play" Height="23" HorizontalAlignment="Left" Margin="10,43,0,0" Name="button2" VerticalAlignment="Top" Width="75" Click="Playbutton_Click" />
<Button Content="stop" Height="23" HorizontalAlignment="Left" Margin="10,142,0,0" Name="button5" VerticalAlignment="Top" Width="75" Click="stopbutton_Click" />
<Button Content="Pause" Height="23" HorizontalAlignment="Left" Margin="12,171,0,0" Name="button6" VerticalAlignment="Top" Width="75" Click="pausebutton_Click" />
<TextBox Height="23" HorizontalAlignment="Left" Margin="165,296,0,0" Name="tb_starttime" VerticalAlignment="Top" Width="120" Text="{Binding ElementName=slider1, Path=Value, Mode=TwoWay}" />
<TextBox Height="23" HorizontalAlignment="Right" Margin="0,296,426,0" Name="tb_endtime" VerticalAlignment="Top" Width="120" Text="{Binding ElementName=slider2, Path=Value, Mode=TwoWay}" />
<TextBox Height="23" HorizontalAlignment="Left" Margin="630,281,0,0" Name="textBox3" VerticalAlignment="Top" Width="120" TextChanged="positionbox_TextChanged" IsReadOnly="False" Text="{Binding ElementName=mediaElement1, Path=Position.Milliseconds, Mode=OneWay, UpdateSourceTrigger=PropertyChanged}" />
<TextBox Height="23" HorizontalAlignment="Left" Margin="490,281,0,0" Name="textBox4" VerticalAlignment="Top" Width="134" />
<Label Content="filename" Height="28" HorizontalAlignment="Left" Margin="104,325,0,0" Name="label1" VerticalAlignment="Top" />
<ListBox Height="215" HorizontalAlignment="Left" Margin="469,10,0,0" Name="listBox1" VerticalAlignment="Top" Width="431" />
<TextBox Height="23" HorizontalAlignment="Left" Margin="165,325,0,0" Name="tb_filename" VerticalAlignment="Top" Width="213" Text="C:\Data\001femod1\vid\dat1.avi" AcceptsTab="False" />
<Label Content="end time" Height="28" HorizontalAlignment="Left" Margin="291,294,0,0" Name="label2" VerticalAlignment="Top" />
<Label Content="start time" Height="28" HorizontalAlignment="Left" Margin="104,296,0,0" Name="label3" VerticalAlignment="Top" />
<Button Content="add to list" Height="23" HorizontalAlignment="Left" Margin="11,315,0,0" Name="button7" VerticalAlignment="Top" Width="75" Click="AddToListbutton_Click" />
<Label Content="Action" Height="28" HorizontalAlignment="Left" Margin="384,325,0,0" Name="label4" VerticalAlignment="Top" />
<ComboBox Height="23" HorizontalAlignment="Left" Margin="434,326,0,0" Name="tb_action" VerticalAlignment="Top" Width="120">
<ComboBoxItem Content="Play" />
<ComboBoxItem Content="Load" />
<ComboBoxItem Content="Stop" />
<ComboBoxItem Content="Pause" />
<ComboBoxItem Content="Seek" />
</ComboBox>
<Button Content="test times" Height="23" HorizontalAlignment="Left" Margin="50,246,0,0" Name="tb_test" VerticalAlignment="Top" Width="75" Click="testbutton_Click" />
<Slider Height="23" Margin="147,231,170,0" Name="slider1" VerticalAlignment="Top" SmallChange="1" LargeChange="10" IsSelectionRangeEnabled="False" IsMoveToPointEnabled="True" IsSnapToTickEnabled="True" ValueChanged="slider1_ValueChanged" />
<Slider Height="23" HorizontalAlignment="Left" Margin="147,260,0,0" Name="slider2" VerticalAlignment="Top" Width="583" SmallChange="1" IsSnapToTickEnabled="True" ValueChanged="slider2_ValueChanged" />
<Label Content="max value" Height="28" HorizontalAlignment="Left" Margin="736,226,0,0" Name="label5" VerticalAlignment="Top" />
<TextBox Height="23" HorizontalAlignment="Left" Margin="736,247,0,0" Name="tb_slider_maxvalue" VerticalAlignment="Top" Width="120" Text="74000" TextChanged="slidermax_values_TextChanged" />
<Button Content="start script" Height="23" HorizontalAlignment="Left" Margin="10,281,0,0" Name="button3" VerticalAlignment="Top" Width="75" Click="start_script_Click" />
<MediaElement Height="215" HorizontalAlignment="Left" Margin="91,10,0,0" Name="mediaElement1" VerticalAlignment="Top" Width="372" MediaOpened="mediaElement1_MediaOpened" />
</Grid>
</Window>
回答2:
Hmmm, that was tldnr for me so I'll offer up a route that worked for me for a UWP project that seems much simpler, but not sure if it'll work in your case:
For skipping to the right spots, use MediaPlayer.PlaybackSession.Position = TimeSpan.FromMilliseconds(yourDesiredPosition);
For knowing when to skip to the right spots (or do whatever else you need to, start, stop, switch source, whatever), just attach a position changed event:
Player.MediaPlayer.PlaybackSession.PositionChanged += PlaybackSession_PositionChanged;
private void PlaybackSession_PositionChanged(MediaPlaybackSession sender, object args)
{
var playa = sender.MediaPlayer;
if(playa.Position >= YourSpecialTimeSpan)
{
//do something, note can check state with sender.PlaybackState
}
}
hope this helps...
来源：https://stackoverflow.com/questions/7336933/start-and-stop-mediaelement-at-specific-times