190 lines
6.0 KiB
XML
190 lines
6.0 KiB
XML
|
<refentry id="vidioc-g-enc-index">
|
||
|
|
<refmeta>
|
||
|
|
<refentrytitle>ioctl VIDIOC_G_ENC_INDEX</refentrytitle>
|
||
|
|
&manvol;
|
||
|
|
</refmeta>
|
||
|
|
|
||
|
|
<refnamediv>
|
||
|
|
<refname>VIDIOC_G_ENC_INDEX</refname>
|
||
|
|
<refpurpose>Get meta data about a compressed video stream</refpurpose>
|
||
|
|
</refnamediv>
|
||
|
|
|
||
|
|
<refsynopsisdiv>
|
||
|
|
<funcsynopsis>
|
||
|
|
<funcprototype>
|
||
|
|
<funcdef>int <function>ioctl</function></funcdef>
|
||
|
|
<paramdef>int <parameter>fd</parameter></paramdef>
|
||
|
|
<paramdef>int <parameter>request</parameter></paramdef>
|
||
|
|
<paramdef>struct v4l2_enc_idx *<parameter>argp</parameter></paramdef>
|
||
|
|
</funcprototype>
|
||
|
|
</funcsynopsis>
|
||
|
|
</refsynopsisdiv>
|
||
|
|
|
||
|
|
<refsect1>
|
||
|
|
<title>Arguments</title>
|
||
|
|
|
||
|
|
<variablelist>
|
||
|
|
<varlistentry>
|
||
|
|
<term><parameter>fd</parameter></term>
|
||
|
|
<listitem>
|
||
|
|
<para>&fd;</para>
|
||
|
|
</listitem>
|
||
|
|
</varlistentry>
|
||
|
|
<varlistentry>
|
||
|
|
<term><parameter>request</parameter></term>
|
||
|
|
<listitem>
|
||
|
|
<para>VIDIOC_G_ENC_INDEX</para>
|
||
|
|
</listitem>
|
||
|
|
</varlistentry>
|
||
|
|
<varlistentry>
|
||
|
|
<term><parameter>argp</parameter></term>
|
||
|
|
<listitem>
|
||
|
|
<para></para>
|
||
|
|
</listitem>
|
||
|
|
</varlistentry>
|
||
|
|
</variablelist>
|
||
|
|
</refsect1>
|
||
|
|
|
||
|
|
<refsect1>
|
||
|
|
<title>Description</title>
|
||
|
|
|
||
|
|
<para>The <constant>VIDIOC_G_ENC_INDEX</constant> ioctl provides
|
||
|
|
meta data about a compressed video stream the same or another
|
||
|
|
application currently reads from the driver, which is useful for
|
||
|
|
random access into the stream without decoding it.</para>
|
||
|
|
|
||
|
|
<para>To read the data applications must call
|
||
|
|
<constant>VIDIOC_G_ENC_INDEX</constant> with a pointer to a
|
||
|
|
&v4l2-enc-idx;. On success the driver fills the
|
||
|
|
<structfield>entry</structfield> array, stores the number of elements
|
||
|
|
written in the <structfield>entries</structfield> field, and
|
||
|
|
initializes the <structfield>entries_cap</structfield> field.</para>
|
||
|
|
|
||
|
|
<para>Each element of the <structfield>entry</structfield> array
|
||
|
|
contains meta data about one picture. A
|
||
|
|
<constant>VIDIOC_G_ENC_INDEX</constant> call reads up to
|
||
|
|
<constant>V4L2_ENC_IDX_ENTRIES</constant> entries from a driver
|
||
|
|
buffer, which can hold up to <structfield>entries_cap</structfield>
|
||
|
|
entries. This number can be lower or higher than
|
||
|
|
<constant>V4L2_ENC_IDX_ENTRIES</constant>, but not zero. When the
|
||
|
|
application fails to read the meta data in time the oldest entries
|
||
|
|
will be lost. When the buffer is empty or no capturing/encoding is in
|
||
|
|
progress, <structfield>entries</structfield> will be zero.</para>
|
||
|
|
|
||
|
|
<para>Currently this ioctl is only defined for MPEG-2 program
|
||
|
|
streams and video elementary streams.</para>
|
||
|
|
|
||
|
|
<table pgwide="1" frame="none" id="v4l2-enc-idx">
|
||
|
|
<title>struct <structname>v4l2_enc_idx</structname></title>
|
||
|
|
<tgroup cols="3">
|
||
|
|
&cs-str;
|
||
|
|
<tbody valign="top">
|
||
|
|
<row>
|
||
|
|
<entry>__u32</entry>
|
||
|
|
<entry><structfield>entries</structfield></entry>
|
||
|
|
<entry>The number of entries the driver stored in the
|
||
|
|
<structfield>entry</structfield> array.</entry>
|
||
|
|
</row>
|
||
|
|
<row>
|
||
|
|
<entry>__u32</entry>
|
||
|
|
<entry><structfield>entries_cap</structfield></entry>
|
||
|
|
<entry>The number of entries the driver can
|
||
|
|
buffer. Must be greater than zero.</entry>
|
||
|
|
</row>
|
||
|
|
<row>
|
||
|
|
<entry>__u32</entry>
|
||
|
|
<entry><structfield>reserved</structfield>[4]</entry>
|
||
|
|
<entry spanname="hspan">Reserved for future extensions.
|
||
|
|
Drivers must set the array to zero.</entry>
|
||
|
|
</row>
|
||
|
|
<row>
|
||
|
|
<entry>&v4l2-enc-idx-entry;</entry>
|
||
|
|
<entry><structfield>entry</structfield>[<constant>V4L2_ENC_IDX_ENTRIES</constant>]</entry>
|
||
|
|
<entry>Meta data about a compressed video stream. Each
|
||
|
|
element of the array corresponds to one picture, sorted in ascending
|
||
|
|
order by their <structfield>offset</structfield>.</entry>
|
||
|
|
</row>
|
||
|
|
</tbody>
|
||
|
|
</tgroup>
|
||
|
|
</table>
|
||
|
|
|
||
|
|
<table pgwide="1" frame="none" id="v4l2-enc-idx-entry">
|
||
|
|
<title>struct <structname>v4l2_enc_idx_entry</structname></title>
|
||
|
|
<tgroup cols="3">
|
||
|
|
&cs-str;
|
||
|
|
<tbody valign="top">
|
||
|
|
<row>
|
||
|
|
<entry>__u64</entry>
|
||
|
|
<entry><structfield>offset</structfield></entry>
|
||
|
|
<entry>The offset in bytes from the beginning of the
|
||
|
|
compressed video stream to the beginning of this picture, that is a
|
||
|
|
<wordasword>PES packet header</wordasword> as defined in <xref
|
||
|
|
linkend="mpeg2part1" /> or a <wordasword>picture
|
||
|
|
header</wordasword> as defined in <xref linkend="mpeg2part2" />. When
|
||
|
|
the encoder is stopped, the driver resets the offset to zero.</entry>
|
||
|
|
</row>
|
||
|
|
<row>
|
||
|
|
<entry>__u64</entry>
|
||
|
|
<entry><structfield>pts</structfield></entry>
|
||
|
|
<entry>The 33 bit <wordasword>Presentation Time
|
||
|
|
Stamp</wordasword> of this picture as defined in <xref
|
||
|
|
linkend="mpeg2part1" />.</entry>
|
||
|
|
</row>
|
||
|
|
<row>
|
||
|
|
<entry>__u32</entry>
|
||
|
|
<entry><structfield>length</structfield></entry>
|
||
|
|
<entry>The length of this picture in bytes.</entry>
|
||
|
|
</row>
|
||
|
|
<row>
|
||
|
|
<entry>__u32</entry>
|
||
|
|
<entry><structfield>flags</structfield></entry>
|
||
|
|
<entry>Flags containing the coding type of this picture, see <xref
|
||
|
|
linkend="enc-idx-flags" />.</entry>
|
||
|
|
</row>
|
||
|
|
<row>
|
||
|
|
<entry>__u32</entry>
|
||
|
|
<entry><structfield>reserved</structfield>[2]</entry>
|
||
|
|
<entry>Reserved for future extensions.
|
||
|
|
Drivers must set the array to zero.</entry>
|
||
|
|
</row>
|
||
|
|
</tbody>
|
||
|
|
</tgroup>
|
||
|
|
</table>
|
||
|
|
|
||
|
|
<table pgwide="1" frame="none" id="enc-idx-flags">
|
||
|
|
<title>Index Entry Flags</title>
|
||
|
|
<tgroup cols="3">
|
||
|
|
&cs-def;
|
||
|
|
<tbody valign="top">
|
||
|
|
<row>
|
||
|
|
<entry><constant>V4L2_ENC_IDX_FRAME_I</constant></entry>
|
||
|
|
<entry>0x00</entry>
|
||
|
|
<entry>This is an Intra-coded picture.</entry>
|
||
|
|
</row>
|
||
|
|
<row>
|
||
|
|
<entry><constant>V4L2_ENC_IDX_FRAME_P</constant></entry>
|
||
|
|
<entry>0x01</entry>
|
||
|
|
<entry>This is a Predictive-coded picture.</entry>
|
||
|
|
</row>
|
||
|
|
<row>
|
||
|
|
<entry><constant>V4L2_ENC_IDX_FRAME_B</constant></entry>
|
||
|
|
<entry>0x02</entry>
|
||
|
|
<entry>This is a Bidirectionally predictive-coded
|
||
|
|
picture.</entry>
|
||
|
|
</row>
|
||
|
|
<row>
|
||
|
|
<entry><constant>V4L2_ENC_IDX_FRAME_MASK</constant></entry>
|
||
|
|
<entry>0x0F</entry>
|
||
|
|
<entry><wordasword>AND</wordasword> the flags field with
|
||
|
|
this mask to obtain the picture coding type.</entry>
|
||
|
|
</row>
|
||
|
|
</tbody>
|
||
|
|
</tgroup>
|
||
|
|
</table>
|
||
|
|
</refsect1>
|
||
|
|
|
||
|
|
<refsect1>
|
||
|
|
&return-value;
|
||
|
|
</refsect1>
|
||
|
|
</refentry>
|