ioctl VIDIOC_G_ENC_INDEX &manvol; VIDIOC_G_ENC_INDEX Get meta data about a compressed video stream int ioctl int fd int request struct v4l2_enc_idx *argp fd &fd; request VIDIOC_G_ENC_INDEX argp The VIDIOC_G_ENC_INDEX 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. To read the data applications must call VIDIOC_G_ENC_INDEX with a pointer to a &v4l2-enc-idx;. On success the driver fills the entry array, stores the number of elements written in the entries field, and initializes the entries_cap field. Each element of the entry array contains meta data about one picture. A VIDIOC_G_ENC_INDEX call reads up to V4L2_ENC_IDX_ENTRIES entries from a driver buffer, which can hold up to entries_cap entries. This number can be lower or higher than V4L2_ENC_IDX_ENTRIES, 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, entries will be zero. Currently this ioctl is only defined for MPEG-2 program streams and video elementary streams. &cs-str; __u32 entries The number of entries the driver stored in the entry array. __u32 entries_cap The number of entries the driver can buffer. Must be greater than zero. __u32 reserved[4] Reserved for future extensions. Drivers must set the array to zero. &v4l2-enc-idx-entry; entry[V4L2_ENC_IDX_ENTRIES] Meta data about a compressed video stream. Each element of the array corresponds to one picture, sorted in ascending order by their offset. &cs-str; __u64 offset The offset in bytes from the beginning of the compressed video stream to the beginning of this picture, that is a PES packet header as defined in or a picture header as defined in . When the encoder is stopped, the driver resets the offset to zero. __u64 pts The 33 bit Presentation Time Stamp of this picture as defined in . __u32 length The length of this picture in bytes. __u32 flags Flags containing the coding type of this picture, see . __u32 reserved[2] Reserved for future extensions. Drivers must set the array to zero. &cs-def; V4L2_ENC_IDX_FRAME_I 0x00 This is an Intra-coded picture. V4L2_ENC_IDX_FRAME_P 0x01 This is a Predictive-coded picture. V4L2_ENC_IDX_FRAME_B 0x02 This is a Bidirectionally predictive-coded picture. V4L2_ENC_IDX_FRAME_MASK 0x0F AND the flags field with this mask to obtain the picture coding type. &return-value;