EVOLUTION-MANAGER

Edit File: example_simple_encoder.html

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/xhtml;charset=UTF-8"/>
<meta http-equiv="X-UA-Compatible" content="IE=9"/>
<meta name="generator" content="Doxygen 1.8.5"/>
<title>WebM VP8 Codec SDK: simple_encoder.c</title>
<link href="tabs.css" rel="stylesheet" type="text/css"/>
<script type="text/javascript" src="jquery.js"></script>
<script type="text/javascript" src="dynsections.js"></script>
<link href="doxygen.css" rel="stylesheet" type="text/css" />
</head>
<body>
<div id="top">
<div id="titlearea">
<table cellspacing="0" cellpadding="0">
 <tbody>
 <tr style="height: 56px;">
 <td style="padding-left: 0.5em;">
 <div id="projectname">WebM VP8 Codec SDK
 </div>
 </td>
 </tr>
 </tbody>
</table>
</div>


 <div id="navrow1" class="tabs">
 <ul class="tablist">
 <li><a href="index.html">Main&#160;Page</a></li>
 <li class="current"><a href="pages.html">Related&#160;Pages</a></li>
 <li><a href="modules.html">Modules</a></li>
 <li><a href="annotated.html">Data&#160;Structures</a></li>
 <li><a href="files.html">Files</a></li>
 </ul>
 </div>
<div id="nav-path" class="navpath">
 <ul>
<li class="navelem"><a class="el" href="samples.html">Sample Code</a></li> </ul>
</div>
</div>
<div class="header">
 <div class="headertitle">
<div class="title">simple_encoder.c </div> </div>
</div>
<div class="contents">
<div class="textblock"> 
<h1>Simple Encoder</h1>

This is an example of a simple encoder loop. It takes an input file in
YV12 format, passes it through the encoder, and writes the compressed
frames to disk in IVF format. Other decoder examples build upon this
one.

The details of the IVF format have been elided from this example for
simplicity of presentation, as IVF files will not generally be used by
your application. In general, an IVF file consists of a file header,
followed by a variable number of frames. Each frame consists of a frame
header followed by a variable length payload. The length of the payload
is specified in the first four bytes of the frame header. The payload is
the raw compressed data.

<h2>Standard Includes</h2>

For encoders, you only have to include <code>vpx_encoder.h</code> and then any
header files for the specific codecs you use. In this case, we&#8217;re using
vp8. The <code>VPX_CODEC_DISABLE_COMPAT</code> macro can be defined to ensure
strict compliance with the latest SDK by disabling some backwards
compatibility features. Defining this macro is encouraged.

<pre class="c">#define VPX_CODEC_DISABLE_COMPAT 1
#include &quot;vpx/vpx_encoder.h&quot;
#include &quot;vpx/vp9cx.h&quot;
#define interface (vpx_codec_vp8_cx())</pre>

<h2>Getting The Default Configuration</h2>

Encoders have the notion of &#8220;usage profiles.&#8221; For example, an encoder
may want to publish default configurations for both a video
conferencing appliction and a best quality offline encoder. These
obviously have very different default settings. Consult the
documentation for your codec to see if it provides any default
configurations. All codecs provide a default configuration, number 0,
which is valid for material in the vacinity of QCIF/QVGA.

<pre class="c">/* Populate encoder configuration */
res = vpx_codec_enc_config_default&#40;interface, &amp;cfg, 0&#41;;
if&#40;res&#41; &#123;
 <a href="http://www.opengroup.org/onlinepubs/009695399/functions/printf.html">printf</a>&#40;&quot;Failed to get config: %s\n&quot;, vpx_codec_err_to_string&#40;res&#41;&#41;;
 return EXIT_FAILURE;
&#125;</pre>

<h2>Updating The Configuration</h2>

Almost all applications will want to update the default configuration
with settings specific to their usage. Here we set the width and height
of the video file to that specified on the command line. We also scale
the default bitrate based on the ratio between the default resolution
and the resolution specified on the command line.

<pre class="c">/* Update the default configuration with our settings */
cfg.rc_target_bitrate = width * height * cfg.rc_target_bitrate
 / cfg.g_w / cfg.g_h;
cfg.g_w = width;
cfg.g_h = height;</pre>

<h2>Initializing The Codec</h2>

The encoder is initialized by the following code.

<pre class="c">/* Initialize codec */
if&#40;vpx_codec_enc_init&#40;&amp;codec, interface, &amp;cfg, 0&#41;&#41;
 die_codec&#40;&amp;codec, &quot;Failed to initialize encoder&quot;&#41;;</pre>

<h2>Encoding A Frame</h2>

The frame is read as a continuous block (size width * height * 3 / 2)
from the input file. If a frame was read (the input file has not hit
EOF) then the frame is passed to the encoder. Otherwise, a NULL
is passed, indicating the End-Of-Stream condition to the encoder. The
<code>frame_cnt</code> is reused as the presentation time stamp (PTS) and each
frame is shown for one frame-time in duration. The flags parameter is
unused in this example. The deadline is set to VPX_DL_REALTIME to
make the example run as quickly as possible.

<pre class="c">frame_avail = read_frame&#40;infile, &amp;raw&#41;;
if&#40;vpx_codec_encode&#40;&amp;codec, frame_avail? &amp;raw : NULL, frame_cnt,
 1, flags, VPX_DL_REALTIME&#41;&#41;
 die_codec&#40;&amp;codec, &quot;Failed to encode frame&quot;&#41;;</pre>

<h2>Processing The Encoded Data</h2>

Each packet of type <code>VPX_CODEC_CX_FRAME_PKT</code> contains the encoded data
for this frame. We write a IVF frame header, followed by the raw data.

<pre class="c">case VPX_CODEC_CX_FRAME_PKT:
 write_ivf_frame_header&#40;outfile, pkt&#41;;
 &#40;void&#41; fwrite&#40;pkt-&gt;data.frame.buf, 1, pkt-&gt;data.frame.sz,
 outfile&#41;;
 break;</pre>

<h2>Cleanup</h2>

The <code>vpx_codec_destroy</code> call frees any memory allocated by the codec.

<pre class="c">vpx_img_free&#40;&amp;raw&#41;;
if&#40;vpx_codec_destroy&#40;&amp;codec&#41;&#41;
 die_codec&#40;&amp;codec, &quot;Failed to destroy codec&quot;&#41;;</pre>

<h2>Error Handling</h2>

This example does not special case any error return codes. If there was
an error, a descriptive message is printed and the program exits. With
few exeptions, vpx_codec functions return an enumerated error status,
with the value <code>0</code> indicating success.

<pre class="c">static void die_codec&#40;vpx_codec_ctx_t *ctx, const char *s&#41; &#123;
 const char *detail = vpx_codec_error_detail&#40;ctx&#41;;
&nbsp;
 <a href="http://www.opengroup.org/onlinepubs/009695399/functions/printf.html">printf</a>&#40;&quot;%s: %s\n&quot;, s, vpx_codec_error&#40;ctx&#41;&#41;;
 if&#40;detail&#41;
 <a href="http://www.opengroup.org/onlinepubs/009695399/functions/printf.html">printf</a>&#40;&quot; %s\n&quot;,detail&#41;;
 exit&#40;EXIT_FAILURE&#41;;
&#125;</pre>

<h1>Putting It All Together</h1>

<pre class="c">/*
 Copyright (c) 2010 The WebM project authors. All Rights Reserved.
 
 Use of this source code is governed by a BSD-style license
 that can be found in the LICENSE file in the root of the source
 tree. An additional intellectual property rights grant can be found
 in the file PATENTS. All contributing project authors may
 be found in the AUTHORS file in the root of the source tree.
 */
&nbsp;
&nbsp;
/*
 This is an example of a simple encoder loop. It takes an input file in
 YV12 format, passes it through the encoder, and writes the compressed
 frames to disk in IVF format. Other decoder examples build upon this
 one.
 
 The details of the IVF format have been elided from this example for
 simplicity of presentation, as IVF files will not generally be used by
 your application. In general, an IVF file consists of a file header,
 followed by a variable number of frames. Each frame consists of a frame
 header followed by a variable length payload. The length of the payload
 is specified in the first four bytes of the frame header. The payload is
 the raw compressed data.
 */
#include &lt;stdio.h&gt;
#include &lt;stdlib.h&gt;
#include &lt;stdarg.h&gt;
#include &lt;string.h&gt;
#define VPX_CODEC_DISABLE_COMPAT 1
#include &quot;vpx/vpx_encoder.h&quot;
#include &quot;vpx/vp8cx.h&quot;
#define interface (vpx_codec_vp8_cx())
#define fourcc 0x30385056
&nbsp;
#define IVF_FILE_HDR_SZ (32)
#define IVF_FRAME_HDR_SZ (12)
&nbsp;
static void mem_put_le16&#40;char *mem, unsigned int val&#41; &#123;
 mem&#91;0&#93; = val;
 mem&#91;1&#93; = val&gt;&gt;8;
&#125;
&nbsp;
static void mem_put_le32&#40;char *mem, unsigned int val&#41; &#123;
 mem&#91;0&#93; = val;
 mem&#91;1&#93; = val&gt;&gt;8;
 mem&#91;2&#93; = val&gt;&gt;16;
 mem&#91;3&#93; = val&gt;&gt;24;
&#125;
&nbsp;
static void die&#40;const char *fmt, ...&#41; &#123;
 va_list ap;
&nbsp;
 va_start&#40;ap, fmt&#41;;
 vprintf&#40;fmt, ap&#41;;
 if&#40;fmt&#91;strlen&#40;fmt&#41;-1&#93; != '\n'&#41;
 <a href="http://www.opengroup.org/onlinepubs/009695399/functions/printf.html">printf</a>&#40;&quot;\n&quot;&#41;;
 exit&#40;EXIT_FAILURE&#41;;
&#125;
&nbsp;
static void die_codec&#40;vpx_codec_ctx_t *ctx, const char *s&#41; &#123; //
 const char *detail = vpx_codec_error_detail&#40;ctx&#41;; //
 //
 <a href="http://www.opengroup.org/onlinepubs/009695399/functions/printf.html">printf</a>&#40;&quot;%s: %s\n&quot;, s, vpx_codec_error&#40;ctx&#41;&#41;; //
 if&#40;detail&#41; //
 <a href="http://www.opengroup.org/onlinepubs/009695399/functions/printf.html">printf</a>&#40;&quot; %s\n&quot;,detail&#41;; //
 exit&#40;EXIT_FAILURE&#41;; //
&#125; //
&nbsp;
static int read_frame&#40;FILE *f, vpx_image_t *img&#41; &#123;
 size_t nbytes, to_read;
 int res = 1;
&nbsp;
 to_read = img-&gt;w*img-&gt;h*3/2;
 nbytes = fread&#40;img-&gt;planes&#91;0&#93;, 1, to_read, f&#41;;
 if&#40;nbytes != to_read&#41; &#123;
 res = 0;
 if&#40;nbytes &gt; 0&#41;
 <a href="http://www.opengroup.org/onlinepubs/009695399/functions/printf.html">printf</a>&#40;&quot;Warning: Read partial frame. Check your width &amp; height!\n&quot;&#41;;
 &#125;
 return res;
&#125;
&nbsp;
static void write_ivf_file_header&#40;FILE *outfile,
 const vpx_codec_enc_cfg_t *cfg,
 int frame_cnt&#41; &#123;
 char header&#91;32&#93;;
&nbsp;
 if&#40;cfg-&gt;g_pass != VPX_RC_ONE_PASS &amp;&amp; cfg-&gt;g_pass != VPX_RC_LAST_PASS&#41;
 return;
 header&#91;0&#93; = 'D';
 header&#91;1&#93; = 'K';
 header&#91;2&#93; = 'I';
 header&#91;3&#93; = 'F';
 mem_put_le16&#40;header+4, 0&#41;; /* version */
 mem_put_le16&#40;header+6, 32&#41;; /* headersize */
 mem_put_le32&#40;header+8, fourcc&#41;; /* headersize */
 mem_put_le16&#40;header+12, cfg-&gt;g_w&#41;; /* width */
 mem_put_le16&#40;header+14, cfg-&gt;g_h&#41;; /* height */
 mem_put_le32&#40;header+16, cfg-&gt;g_timebase.den&#41;; /* rate */
 mem_put_le32&#40;header+20, cfg-&gt;g_timebase.num&#41;; /* scale */
 mem_put_le32&#40;header+24, frame_cnt&#41;; /* length */
 mem_put_le32&#40;header+28, 0&#41;; /* unused */
&nbsp;
 &#40;void&#41; fwrite&#40;header, 1, 32, outfile&#41;;
&#125;
&nbsp;
&nbsp;
static void write_ivf_frame_header&#40;FILE *outfile,
 const vpx_codec_cx_pkt_t *pkt&#41;
&#123;
 char header&#91;12&#93;;
 vpx_codec_pts_t pts;
&nbsp;
 if&#40;pkt-&gt;kind != VPX_CODEC_CX_FRAME_PKT&#41;
 return;
&nbsp;
 pts = pkt-&gt;data.frame.pts;
 mem_put_le32&#40;header, pkt-&gt;data.frame.sz&#41;;
 mem_put_le32&#40;header+4, pts&amp;0xFFFFFFFF&#41;;
 mem_put_le32&#40;header+8, pts &gt;&gt; 32&#41;;
&nbsp;
 &#40;void&#41; fwrite&#40;header, 1, 12, outfile&#41;;
&#125;
&nbsp;
int main&#40;int argc, char **argv&#41; &#123;
 FILE *infile, *outfile;
 vpx_codec_ctx_t codec;
 vpx_codec_enc_cfg_t cfg;
 int frame_cnt = 0;
 vpx_image_t raw;
 vpx_codec_err_t res;
 long width;
 long height;
 int frame_avail;
 int got_data;
 int flags = 0;
&nbsp;
 /* Open files */
 if&#40;argc!=5&#41;
 die&#40;&quot;Usage: %s &lt;width&gt; &lt;height&gt; &lt;infile&gt; &lt;outfile&gt;\n&quot;, argv&#91;0&#93;&#41;;
 width = strtol&#40;argv&#91;1&#93;, NULL, 0&#41;;
 height = strtol&#40;argv&#91;2&#93;, NULL, 0&#41;;
 if&#40;width &lt; 16 || width%2 || height &lt;16 || height%2&#41;
 die&#40;&quot;Invalid resolution: %ldx%ld&quot;, width, height&#41;;
 if&#40;!vpx_img_alloc&#40;&amp;raw, VPX_IMG_FMT_I420, width, height, 1&#41;&#41;
 die&#40;&quot;Faile to allocate image&quot;, width, height&#41;;
 if&#40;!&#40;outfile = fopen&#40;argv&#91;4&#93;, &quot;wb&quot;&#41;&#41;&#41;
 die&#40;&quot;Failed to open %s for writing&quot;, argv&#91;4&#93;&#41;;
&nbsp;
 <a href="http://www.opengroup.org/onlinepubs/009695399/functions/printf.html">printf</a>&#40;&quot;Using %s\n&quot;,vpx_codec_iface_name&#40;interface&#41;&#41;;
&nbsp;
 /* Populate encoder configuration */ //
 res = vpx_codec_enc_config_default&#40;interface, &amp;cfg, 0&#41;; //
 if&#40;res&#41; &#123; //
 <a href="http://www.opengroup.org/onlinepubs/009695399/functions/printf.html">printf</a>&#40;&quot;Failed to get config: %s\n&quot;, vpx_codec_err_to_string&#40;res&#41;&#41;; //
 return EXIT_FAILURE; //
 &#125; //
&nbsp;
 /* Update the default configuration with our settings */ //
 cfg.rc_target_bitrate = width * height * cfg.rc_target_bitrate //
 / cfg.g_w / cfg.g_h; //
 cfg.g_w = width; //
 cfg.g_h = height; //
&nbsp;
 write_ivf_file_header&#40;outfile, &amp;cfg, 0&#41;;
&nbsp;
&nbsp;
 /* Open input file for this encoding pass */
 if&#40;!&#40;infile = fopen&#40;argv&#91;3&#93;, &quot;rb&quot;&#41;&#41;&#41;
 die&#40;&quot;Failed to open %s for reading&quot;, argv&#91;3&#93;&#41;;
&nbsp;
 /* Initialize codec */ //
 if&#40;vpx_codec_enc_init&#40;&amp;codec, interface, &amp;cfg, 0&#41;&#41; //
 die_codec&#40;&amp;codec, &quot;Failed to initialize encoder&quot;&#41;; //
&nbsp;
 frame_avail = 1;
 got_data = 0;
 while&#40;frame_avail || got_data&#41; &#123;
 vpx_codec_iter_t iter = NULL;
 const vpx_codec_cx_pkt_t *pkt;
&nbsp;
 frame_avail = read_frame&#40;infile, &amp;raw&#41;; //
 if&#40;vpx_codec_encode&#40;&amp;codec, frame_avail? &amp;raw : NULL, frame_cnt, //
 1, flags, VPX_DL_REALTIME&#41;&#41; //
 die_codec&#40;&amp;codec, &quot;Failed to encode frame&quot;&#41;; //
 got_data = 0;
 while&#40; &#40;pkt = vpx_codec_get_cx_data&#40;&amp;codec, &amp;iter&#41;&#41; &#41; &#123;
 got_data = 1;
 switch&#40;pkt-&gt;kind&#41; &#123;
 case VPX_CODEC_CX_FRAME_PKT: //
 write_ivf_frame_header&#40;outfile, pkt&#41;; //
 &#40;void&#41; fwrite&#40;pkt-&gt;data.frame.buf, 1, pkt-&gt;data.frame.sz, //
 outfile&#41;; //
 break; //
 default:
 break;
 &#125;
 <a href="http://www.opengroup.org/onlinepubs/009695399/functions/printf.html">printf</a>&#40;pkt-&gt;kind == VPX_CODEC_CX_FRAME_PKT
 &amp;&amp; &#40;pkt-&gt;data.frame.flags &amp; VPX_FRAME_IS_KEY&#41;? &quot;K&quot;:&quot;.&quot;&#41;;
 fflush&#40;stdout&#41;;
 &#125;
 frame_cnt++;
 &#125;
 <a href="http://www.opengroup.org/onlinepubs/009695399/functions/printf.html">printf</a>&#40;&quot;\n&quot;&#41;;
 fclose&#40;infile&#41;;
&nbsp;
 <a href="http://www.opengroup.org/onlinepubs/009695399/functions/printf.html">printf</a>&#40;&quot;Processed %d frames.\n&quot;,frame_cnt-1&#41;;
 vpx_img_free&#40;&amp;raw&#41;; //
 if&#40;vpx_codec_destroy&#40;&amp;codec&#41;&#41; //
 die_codec&#40;&amp;codec, &quot;Failed to destroy codec&quot;&#41;; //
&nbsp;
 /* Try to rewrite the file header with the actual frame count */
 if&#40;!fseek&#40;outfile, 0, SEEK_SET&#41;&#41;
 write_ivf_file_header&#40;outfile, &amp;cfg, frame_cnt-1&#41;;
 fclose&#40;outfile&#41;;
 return EXIT_SUCCESS;
&#125;</pre>
 </div></div>

<hr class="footer"/><address class="footer">
Generated by &#160;<a href="http://www.doxygen.org/index.html">
<img class="footer" src="doxygen.png" alt="doxygen"/>
</a> 1.8.5
</address>
</body>
</html>