Merge pull request #369 (update installation instructions)

Silence trim

index.html

@@ -453,7 +453,7 @@
         <dt>-b:v 690k</dt><dd>specifies the 690k video bitrate</dd>
         <dt><em>output file</em></dt><dd>path, name and extension of the output file (make sure to include the <code>.ogv</code> filename suffix)</dd>
       </dl>
-      <p>This recipe is based on <a href="http://paulrouget.com/e/converttohtml5video">Paul Rouget's recipes</a>.</p>
+      <p>This recipe is based on <a href="http://paulrouget.com/e/converttohtml5video" target="_blank">Paul Rouget's recipes</a>.</p>
       <p class="link"></p>
     </div>
     <!-- ends Transcode to Ogg/Theora -->
@@ -713,6 +713,26 @@
       <p class="link"></p>
     </div>
     <!-- ends Modify speed -->
+      
+    <!-- Synchronize video and audio streams -->
+    <label class="recipe" for="sync_streams">Synchronize video and audio streams</label>
+    <input type="checkbox" id="sync_streams">
+    <div class="hiding">
+      <h3>Synchronize video and audio streams</h3>
+      <p><code>ffmpeg -i <em>input_file</em> -itsoffset 0.125 -i <em>input_file</em> -map 1:v -map 0:a -c copy <em>output_file</em></code></p>
+      <p>A command to slip the video channel approximate 2 frames (0.125 for a 25fps timeline) to align video and audio drift, if generated during video tape capture for example.</p>
+      <dl>
+        <dt>ffmpeg</dt><dd>starts the command</dd>
+        <dt>-i <em>input_file</em></dt><dd>path, name and extension of the input file</dd>
+        <dt>-itsoffset 0.125</dt><dd>uses itsoffset command to set offset to 0.125 of a second. The offset time must be a time duration specification, see <a href="https://ffmpeg.org/ffmpeg-utils.html#time-duration-syntax" target="_blank">FFMPEG Utils Time Duration Syntax</a>.</dd>
+        <dt>-i <em>input_file</em></dt><dd>repeat path, name and extension of the input file</dd>
+        <dt>-map 1:v -map 0:a</dt><dd>selects the video channel for itsoffset command. To slip the audio channel reverse the selection to -map 0:v -map 1:a.</dd>
+        <dt>-c copy</dt><dd>copies the encode settings of the input_file to the output_file</dd>
+        <dt><em>output_file_resync</em></dt><dd>path, name and extension of the output_file</dd>
+      </dl>
+      <p class="link"></p>
+    </div>
+    <!-- ends Synchronize video and audio streams -->
 
     <!-- Make stream properties explicate -->
     <label class="recipe" for="clarify_stream">Clarify stream properties</label>
@@ -801,7 +821,7 @@
         <dt>ffmpeg</dt><dd>starts the command</dd>
         <dt>-i <em>input_file</em></dt><dd>path, name and extension of the input file</dd>
         <dt>-c:v prores_ks</dt><dd>encodes the video to ProRes (prores_ks marks the stream as interlaced, unlike prores)</dd>
-        <dt>-flags +ildct</dt><dd>ensures that the output_file has interlaced field encoding, using interlace aware discrete cosine transform</em></dd>
+        <dt>-flags +ildct</dt><dd>ensures that the output_file has interlaced field encoding, using interlace aware discrete cosine transform</dd>
         <dt>-map 0</dt><dd>ensures ffmpeg maps all streams of the input_file to the output_file</dd>
         <dt>-c:a copy</dt><dd>copies the encode settings of the input_file to the output_file</dd>
         <dt><em>output_file</em></dt><dd>path, name and extension of the output file</dd>
@@ -995,7 +1015,7 @@
 
     </div>
     <div class="well">
-    <h2 id="join-trim">Join, trim, or excerpt a video</h2>
+    <h2 id="join-trim">Join, trim, or create an excerpt</h2>
 
     <!-- Join files of the same type together -->
     <label class="recipe" for="join_files">Join (concatenate) two or more files of the same type</label>
@@ -1069,12 +1089,12 @@
       <p>(The Lanczos scaling algorithm is recommended, as it is slower but better than the default bilinear algorithm).</p>
       <p>The rescaling should be applied just before the point where the streams to be used in the output file are listed. Select the stream you want to rescale, apply the filter, and assign that to a variable name (<code>rescaled_video</code> in the below example). Then you use this variable name in the list of streams to be concatenated.</p>
       <p><code>ffmpeg -i input_1.avi -i input_2.mp4 -filter_complex "[0:v:0] scale=1920:1080:flags=lanczos [rescaled_video], [rescaled_video] [0:a:0] [1:v:0] [1:a:0] concat=n=2:v=1:a=1 [video_out] [audio_out]" -map "[video_out]" -map "[audio_out]" <em>output_file</em></code></p>
-      <p>However, this will only have the desired visual output if the inputs have the same aspect ratio. If you wish to concatenate an SD and an HD file, you will also wish to pillarbox the SD file while upscaling. (See the <a href="https://amiaopensource.github.io/ffmprovisr/#SD_HD_2">Convert 4:3 to pillarboxed HD</a> command). The full command would look like this:</p>
+      <p>However, this will only have the desired visual output if the inputs have the same aspect ratio. If you wish to concatenate an SD and an HD file, you will also wish to pillarbox the SD file while upscaling. (See the <a href="#SD_HD_2">Convert 4:3 to pillarboxed HD</a> command). The full command would look like this:</p>
       <p><code>ffmpeg -i input_1.avi -i input_2.mp4 -filter_complex "[0:v:0] scale=1440:1080:flags=lanczos, pad=1920:1080:(ow-iw)/2:(oh-ih)/2 [to_hd_video], [to_hd_video] [0:a:0] [1:v:0] [1:a:0] concat=n=2:v=1:a=1 [video_out] [audio_out]" -map "[video_out]" -map "[audio_out]" <em>output_file</em></code></p>
       <p>Here, the first input is an SD file which needs to be upscaled to match the second input, which is 1920x1080. The scale filter enlarges the SD input to the height of the HD frame, keeping the 4:3 aspect ratio; then, the video is pillarboxed within a 1920x1080 frame.</p>
       <h4>Variation: concatenating files of different framerates</h4>
       <p>If the input files have different framerates, then the output file may be of variable framerate. To explicitly obtain an output file of constant framerate, you may wish convert an input (or multiple inputs) to a different framerate prior to concatenation.</p>
-      <p>You can speed up or slow down a file using the <code>fps</code> and <code>atempo</code> filters (see also the <a href="https://amiaopensource.github.io/ffmprovisr/#modify_speed">Modify speed</a> command).</p>
+      <p>You can speed up or slow down a file using the <code>fps</code> and <code>atempo</code> filters (see also the <a href="#modify_speed">Modify speed</a> command).</p>
       <p>Here's an example of the full command, in which input_1 is 30fps, input_2 is 25fps, and 25fps is the desired output speed.</p>
       <p><code>ffmpeg -i input_1.avi -i input_2.mp4 -filter_complex "[0:v:0] fps=fps=25 [video_to_25fps]; [0:a:0] atempo=(25/30) [audio_to_25fps]; [video_to_25fps] [audio_to_25fps] [1:v:0] [1:a:0] concat=n=2:v=1:a=1 [video_out] [audio_out]" -map "[video_out]" -map "[audio_out]" <em>output_file</em></code></p>
       <p>Note that the <code>fps</code> filter will drop or repeat frames as necessary in order to achieve the desired frame rate - see the FFmpeg <a href="https://ffmpeg.org/ffmpeg-filters.html#fps-1" target="_blank">fps docs</a> for more details.</p>
@@ -1115,12 +1135,12 @@
     <!-- ends Split file into segments -->
 
     <!-- Trim -->
-    <label class="recipe" for="trim">Trim video</label>
+    <label class="recipe" for="trim">Trim file</label>
     <input type="checkbox" id="trim">
     <div class="hiding">
       <h3>Trim a video without re-encoding</h3>
       <p><code>ffmpeg -i <em>input_file</em> -ss 00:02:00 -to 00:55:00 -c copy -map 0 <em>output_file</em></code></p>
-      <p>This command allows you to create an excerpt from a video file without re-encoding the image data.</p>
+      <p>This command allows you to create an excerpt from a file without re-encoding the audiovisual data.</p>
       <dl>
         <dt>ffmpeg</dt><dd>starts the command</dd>
         <dt>-i <em>input_file</em></dt><dd>path, name and extension of the input file</dd>
@@ -1131,7 +1151,7 @@
         <strong>Note:</strong> watch out when using <code>-ss</code> with <code>-c copy</code> if the source is encoded with an interframe codec (e.g., H.264). Since FFmpeg must split on i-frames, it will seek to the nearest i-frame to begin the stream copy.</dd>
         <dt><em>output_file</em></dt><dd>path, name and extension of the output file</dd>
       </dl>
-      <p>Variation: trim video by setting duration, by using <code>-t</code> instead of <code>-to</code></p>
+      <p>Variation: trim file by setting duration, by using <code>-t</code> instead of <code>-to</code></p>
       <p><code>ffmpeg -i <em>input_file</em> -ss 00:05:00 -t 10 -c copy <em>output_file</em></code></p>
       <dl>
         <dt>-ss 00:05:00 -t 10</dt><dd>Beginning five minutes into the original video, this command will create a 10-second-long excerpt.</dd>
@@ -1147,7 +1167,7 @@
     <div class="hiding">
       <h3>Excerpt from beginning</h3>
       <p><code>ffmpeg -i <em>input_file</em> -t <em>5</em> -c copy -map 0 <em>output_file</em></code></p>
-      <p>This command captures a certain portion of a video file, starting from the beginning and continuing for the amount of time (in seconds) specified in the script. This can be used to create a preview file, or to remove unwanted content from the end of the file. To be more specific, use timecode, such as 00:00:05.</p>
+      <p>This command captures a certain portion of a file, starting from the beginning and continuing for the amount of time (in seconds) specified in the script. This can be used to create a preview file, or to remove unwanted content from the end of the file. To be more specific, use timecode, such as 00:00:05.</p>
       <dl>
         <dt>ffmpeg</dt><dd>starts the command</dd>
         <dt>-i <em>input_file</em></dt><dd>path, name and extension of the input file</dd>
@@ -1161,12 +1181,12 @@
     <!-- ends Excerpt from beginning -->
 
     <!-- Excerpt to end -->
-    <label class="recipe" for="excerpt_to_end">Create a new video file with the first five seconds trimmed off the original</label>
+    <label class="recipe" for="excerpt_to_end">Create a new file with the first five seconds trimmed off the original</label>
     <input type="checkbox" id="excerpt_to_end">
     <div class="hiding">
       <h3>Excerpt to end</h3>
       <p><code>ffmpeg -i <em>input_file</em> -ss <em>5</em> -c copy -map 0 <em>output_file</em></code></p>
-      <p>This command copies a video file starting from a specified time, removing the first few seconds from the output. This can be used to create an excerpt, or remove unwanted content from the beginning of a video file.</p>
+      <p>This command copies a file starting from a specified time, removing the first few seconds from the output. This can be used to create an excerpt, or remove unwanted content from the beginning of a file.</p>
       <dl>
         <dt>ffmpeg</dt><dd>starts the command</dd>
         <dt>-i <em>input_file</em></dt><dd>path, name and extension of the input file</dd>
@@ -1180,12 +1200,12 @@
     <!-- ends Excerpt to end -->
 
     <!-- Excerpt from end -->
-    <label class="recipe" for="excerpt_from_end">Create a new video file with the final five seconds of the original</label>
+    <label class="recipe" for="excerpt_from_end">Create a new file with the final five seconds of the original</label>
     <input type="checkbox" id="excerpt_from_end">
     <div class="hiding">
       <h3>Excerpt from end</h3>
       <p><code>ffmpeg -sseof <em>-5</em> -i <em>input_file</em> -c copy -map 0 <em>output_file</em></code></p>
-      <p>This command copies a video file starting from a specified time before the end of the file, removing everything before from the output. This can be used to create an excerpt, or extract content from the end of a video file (e.g. for extracting the closing credits).</p>
+      <p>This command copies a file starting from a specified time before the end of the file, removing everything before from the output. This can be used to create an excerpt, or extract content from the end of a file (e.g. for extracting the closing credits).</p>
       <dl>
         <dt>ffmpeg</dt><dd>starts the command</dd>
         <dt>-sseof <em>-5</em></dt><dd>This parameter must stay before the input file. It tells FFmpeg what timecode in the file to look for to start copying, and specifies the number of seconds from the end of the video that FFmpeg should start copying. The end of the file has index 0 and the minus sign is needed to reference earlier portions. To be more specific, you can use timecode such as -00:00:05. Note that in most file formats it is not possible to seek exactly, so FFmpeg will seek to the closest point before.</dd>
@@ -1198,6 +1218,50 @@
     </div>
     <!-- ends Excerpt from end -->
 
+    <!-- Trim start silence -->
+    <label class="recipe" for="trim_start_silence">Trim silence from beginning of an audio file</label>
+    <input type="checkbox" id="trim_start_silence">
+    <div class="hiding">
+      <h3>Remove silent portion at the beginning of an audio file</h3>
+      <p><code>ffmpeg -i <em>input_file</em> -af silenceremove=start_threshold=-57dB:start_duration=1:start_periods=1  -c:a <em>your_codec_choice</em> -ar <em>your_sample_rate_choice</em> <em>output_file</em></code></p>
+      <p>This command will automatically remove silence at the beginning of an audio file. The threshold for what qualifies as silence can be changed - this example uses anything under -57 dB, which is a decent level for accounting for analogue hiss.</p>
+      <p><strong>Note:</strong> Since this command uses a filter, the audio stream will be re-encoded for the output. If you do not specify a sample rate or codec, this command will use the sample rate from your input and <a href='#codec-defaults'>the codec defaults for your output format</a>. Take care that you are getting your intended results!</p>
+      <dl>
+        <dt>ffmpeg</dt><dd>starts the command</dd>
+        <dt>-i <em>input_file</em></dt><dd>path, name and extension of the input file (e.g. input_file.wav)</dd>
+        <dt>-af silenceremove</dt><dd>applies the silence remove filter</dd>
+        <dt>start_threshold=-57dB</dt><dd>tells the filter the threshold for what to call 'silence' for the purpose of removal. This can be increased or decreased as necessary.</dd>
+        <dt>start_duration=1</dt><dd>This tells the filter how much non-silent audio must be detected before it stops trimming. With a value of <code>0</code> the filter would stop after detecting any non-silent audio. A setting of <code>1</code> allows it to continue trimming through short 'pops' such as those caused by engaging the playback device, or the recorded sound of a microphone being plugged in.</dd>
+        <dt>start_periods=1</dt><dd>This tells the filter to trim the first example of silence it discovers from the beginning of the file. This value could be increased to remove subsequent silent portions from the file if desired.</dd>
+        <dt>-c:a <em>your_codec_choice</em></dt><dd>This tells the filter what codec to use, and must be specified to avoid defaults. If you want 24 bit PCM, your value would be <code>-c:a pcm_s24le</code>.</dd>
+        <dt><em>output_file</em></dt><dd>path, name and extension of the output file (e.g. output_file.wav).</dd>
+      </dl>
+    </div>
+    <!-- ends Trim start silence -->
+
+    <!-- Trim end silence -->
+    <label class="recipe" for="trim_end_silence">Trim silence from the end of an audio file</label>
+    <input type="checkbox" id="trim_end_silence">
+    <div class="hiding">
+      <h3>Remove silent portion from the end of an audio file</h3>
+      <p><code>ffmpeg -i <em>input_file</em> -af areverse,silenceremove=start_threshold=-57dB:start_duration=1:start_periods=1,areverse -c:a <em>your_codec_choice</em> -ar <em>your_sample_rate_choice</em> <em>output_file</em></code></p>
+      <p>This command will automatically remove silence at the end of an audio file. Since the <code>silenceremove</code> filter is best at removing silence from the beginning of files, this command used the <code>areverse</code> filter twice to reverse the input, remove silence and then restore correct orientation.</p>
+      <p><strong>Note:</strong> Since this command uses a filter, the audio stream will be re-encoded for the output. If you do not specify a sample rate or codec, this command will use the sample rate from your input and <a href='#codec-defaults'>the codec defaults for your output format</a>. Take care that you are getting your intended results!</p>
+      <dl>
+        <dt>ffmpeg</dt><dd>starts the command</dd>
+        <dt>-i <em>input_file</em></dt><dd>path, name and extension of the input file (e.g. input_file.wav)</dd>
+        <dt>-af areverse,</dt><dd>starts the filter chain with reversing the input</dd>
+        <dt>silenceremove</dt><dd>applies the silence remove filter</dd>
+        <dt>start_threshold=-57dB</dt><dd>tells the filter the threshold for what to call 'silence' for the purpose of removal. This can be increased or decreased as necessary.</dd>
+        <dt>start_duration=1</dt><dd>This tells the filter how much non-silent audio must be detected before it stops trimming. With a value of <code>0</code> the filter would stop after detecting any non-silent audio. A setting of <code>1</code> allows it to continue trimming through short 'pops' such as those caused by engaging the playback device, or the recorded sound of a microphone being plugged in.</dd>
+        <dt>start_periods=1</dt><dd>This tells the filter to trim the first example of silence it discovers.</dd>
+        <dt>areverse</dt><dd>applies the audio reverse filter again to restore input to correct orientation.</dd>
+        <dt>-c:a <em>your_codec_choice</em></dt><dd>This tells the filter what codec to use, and must be specified to avoid defaults. If you want 24 bit PCM, your value would be <code>-c:a pcm_s24le</code>.</dd>
+        <dt><em>output_file</em></dt><dd>path, name and extension of the output file (e.g. output_file.wav).</dd>
+      </dl>
+    </div>
+    <!-- ends Trim end silence -->
+
     </div>
     <div class="well">
     <h2 id="interlacing">Work with interlaced video</h2>
@@ -1251,7 +1315,7 @@
       <p><code>"yadif,format=yuv420p"</code> is an FFmpeg <a href="https://trac.ffmpeg.org/wiki/FilteringGuide#FiltergraphChainFilterrelationship" target="_blank">filtergraph</a>. Here the filtergraph is made up of one filter chain, which is itself made up of the two filters (separated by the comma).<br>
       The enclosing quote marks are necessary when you use spaces within the filtergraph, e.g. <code>-vf "yadif, format=yuv420p"</code>, and are included above as an example of good practice.</p>
       <p><strong>Note:</strong> FFmpeg includes several deinterlacers apart from <a href="https://ffmpeg.org/ffmpeg-filters.html#yadif-1" target="_blank">yadif</a>: <a href="https://ffmpeg.org/ffmpeg-filters.html#bwdif" target="_blank">bwdif</a>, <a href="https://ffmpeg.org/ffmpeg-filters.html#w3fdif" target="_blank">w3fdif</a>, <a href="https://ffmpeg.org/ffmpeg-filters.html#kerndeint" target="_blank">kerndeint</a>, and <a href="https://ffmpeg.org/ffmpeg-filters.html#nnedi" target="_blank">nnedi</a>.</p>
-      <p>For more H.264 encoding options, see the latter section of the <a href="./index.html#transcode_h264">encode H.264 command</a>.</p>
+      <p>For more H.264 encoding options, see the latter section of the <a href="#transcode_h264">encode H.264 command</a>.</p>
       <div class="sample-image">
         <h2>Example</h2>
         <p>Before and after deinterlacing:</p>
@@ -1797,7 +1861,7 @@
     <input type="checkbox" id="batch_processing_win">
     <div class="hiding">
       <h3>Create PowerShell script to batch process with FFmpeg</h3>
-      <p>As of Windows 10, it is possible to run Bash via <a href="https://msdn.microsoft.com/en-us/commandline/wsl/about" target="_blank">Bash on Ubuntu on Windows</a>, allowing you to use <a href="index.html#batch_processing_bash">bash scripting</a>. To enable Bash on Windows, see <a href="https://msdn.microsoft.com/en-us/commandline/wsl/install_guide" target="_blank">these instructions</a>.</p>
+      <p>As of Windows 10, it is possible to run Bash via <a href="https://msdn.microsoft.com/en-us/commandline/wsl/about" target="_blank">Bash on Ubuntu on Windows</a>, allowing you to use <a href="#batch_processing_bash">bash scripting</a>. To enable Bash on Windows, see <a href="https://msdn.microsoft.com/en-us/commandline/wsl/install_guide" target="_blank">these instructions</a>.</p>
       <p>On Windows, the primary native command line program is <strong>PowerShell</strong>. PowerShell scripts are plain text files saved with a .ps1 extension. This entry explains how they work with the example of a PowerShell script named “rewrap-mp4.ps1”, which rewraps .mp4 files in a given directory to .mkv files.</p>
       <p>“rewrap-mp4.ps1” contains the following text:</p>
       <pre class="codeblock"><code>$inputfiles = ls *.mp4
@@ -1942,7 +2006,7 @@
         <dt>-loglevel error</dt><dd>sets the verbosity of logging to show all errors</dd>
         <dt>-i <em>input_file</em></dt><dd>path, name and extension of the input file</dd>
         <dt>-map 0:v:0</dt><dd>designated the first video stream as the stream on which to perform this hash generation operation. <code>-map 0</code> can be used to run the operation on all streams.</dd>
-        <dt>-f hash -hash md5</dt><dd>produce a checksum hash, and set the hash algorithm to md5. See the official <a href="https://ffmpeg.org/ffmpeg-formats.html#hash">documentation on hash</a> for other algorithms.</dd>
+        <dt>-f hash -hash md5</dt><dd>produce a checksum hash, and set the hash algorithm to md5. See the official <a href="https://ffmpeg.org/ffmpeg-formats.html#hash" target="_blank">documentation on hash</a> for other algorithms.</dd>
         <dt>-</dt><dd>FFmpeg syntax requires a specified output, and <code>-</code> is just a place holder. No file is actually created.</dd>
       </dl>
       <p class="link"></p>
@@ -2497,7 +2561,7 @@
       <input type="checkbox" id="find-offset">
       <div class="hiding">
         <h3>Find Drive Offset for Exact CD Ripping</h3>
-        <p>If you want to make CD rips that can be verified via checksums to other rips of the same content, you need to know the offset of your CD drive. Put simply, different models of CD drives have different offsets, meaning they start reading in slightly different locations. This must be compensated for in order for files created on different (model) drives to generate the same checksum. For a more detailed explanation of drive offsets see the explanation <a href="http://dbpoweramp.com/spoons-audio-guide-cd-ripping.htm">here.</a> In order to find your drive offset, first you will need to know exactly what model your drive is, then you can look it up in the list of drive offsets by Accurate Rip.</p>
+        <p>If you want to make CD rips that can be verified via checksums to other rips of the same content, you need to know the offset of your CD drive. Put simply, different models of CD drives have different offsets, meaning they start reading in slightly different locations. This must be compensated for in order for files created on different (model) drives to generate the same checksum. For a more detailed explanation of drive offsets see the explanation <a href="https://dbpoweramp.com/spoons-audio-guide-cd-ripping.htm" target="_blank">here.</a> In order to find your drive offset, first you will need to know exactly what model your drive is, then you can look it up in the list of drive offsets by Accurate Rip.</p>
         <p>Often it can be difficult to tell what model your drive is simply by looking at it - it may be housed inside your computer or have external branding that is different from the actual drive manufacturer. For this reason, it can be useful to query your drive with CD ripping software in order to ID it. The following commands should give you a better idea of what drive you have.</p>
         <p><strong>Cdda2wav:</strong> <code>cdda2wav -scanbus</code> or simply <code>cdda2wav</code></p>
         <p><strong>CD Paranoia:</strong> <code>cdparanoia -vsQ</code></p>

readme.md

@@ -12,9 +12,10 @@ To facilitate better understanding of FFmpeg through collaborative sharing of us
 
 The code is found in the gh-pages branch (the default primary branch). Readme is right here. You can see the site live on [GitHub pages](http://amiaopensource.github.io/ffmprovisr).
 
-You can also install the latest [release](https://github.com/amiaopensource/ffmprovisr/releases) on your computer with the command:
+You can also install the latest [release](https://github.com/amiaopensource/ffmprovisr/releases) on your computer with the two commands:
 ```
-brew install amiaopensource/amiaos/ffmprovisr
+brew tap amiaopensource/amiaos
+brew install ffmprovisr
 ```
 and then call it locally with the command:
 ```