多媒体

开发平台：
MultiPlatform

theora.c：源码内容
							/*****************************************************************************
 * theora.c: theora decoder module making use of libtheora.
 *****************************************************************************
 * Copyright (C) 1999-2001 VideoLAN
 * $Id: theora.c 8813 2004-09-26 20:17:50Z gbazin $
 *
 * Authors: Gildas Bazin <gbazin@videolan.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111, USA.
 *****************************************************************************/
/*****************************************************************************
 * Preamble
 *****************************************************************************/
#include <vlc/vlc.h>
#include <vlc/decoder.h>
#include <vlc/input.h>
#include <vlc/sout.h>
#include <ogg/ogg.h>
#include <theora/theora.h>
/*****************************************************************************
 * decoder_sys_t : theora decoder descriptor
 *****************************************************************************/
struct decoder_sys_t
{
    /* Module mode */
    vlc_bool_t b_packetizer;
    /*
     * Input properties
     */
    int i_headers;
    /*
     * Theora properties
     */
    theora_info      ti;                        /* theora bitstream settings */
    theora_comment   tc;                            /* theora comment header */
    theora_state     td;                   /* theora bitstream user comments */
    /*
     * Common properties
     */
    mtime_t i_pts;
};
/*****************************************************************************
 * Local prototypes
 *****************************************************************************/
static int  OpenDecoder   ( vlc_object_t * );
static int  OpenPacketizer( vlc_object_t * );
static void CloseDecoder  ( vlc_object_t * );
static void *DecodeBlock  ( decoder_t *, block_t ** );
static int  ProcessHeaders( decoder_t * );
static void *ProcessPacket ( decoder_t *, ogg_packet *, block_t ** );
static picture_t *DecodePacket( decoder_t *, ogg_packet * );
static void ParseTheoraComments( decoder_t * );
static void theora_CopyPicture( decoder_t *, picture_t *, yuv_buffer * );
static int  OpenEncoder( vlc_object_t *p_this );
static void CloseEncoder( vlc_object_t *p_this );
static block_t *Encode( encoder_t *p_enc, picture_t *p_pict );
/*****************************************************************************
 * Module descriptor
 *****************************************************************************/
#define ENC_QUALITY_TEXT N_("Encoding quality")
#define ENC_QUALITY_LONGTEXT N_( 
  "Allows you to specify a quality between 1 (low) and 10 (high), instead " 
  "of specifying a particular bitrate. This will produce a VBR stream." )
vlc_module_begin();
    set_description( _("Theora video decoder") );
    set_capability( "decoder", 100 );
    set_callbacks( OpenDecoder, CloseDecoder );
    add_shortcut( "theora" );
    add_submodule();
    set_description( _("Theora video packetizer") );
    set_capability( "packetizer", 100 );
    set_callbacks( OpenPacketizer, CloseDecoder );
    add_shortcut( "theora" );
    add_submodule();
    set_description( _("Theora video encoder") );
    set_capability( "encoder", 100 );
    set_callbacks( OpenEncoder, CloseEncoder );
    add_shortcut( "theora" );
#   define ENC_CFG_PREFIX "sout-theora-"
    add_integer( ENC_CFG_PREFIX "quality", 2, NULL, ENC_QUALITY_TEXT,
                 ENC_QUALITY_LONGTEXT, VLC_FALSE );
vlc_module_end();
static const char *ppsz_enc_options[] = {
    "quality", NULL
};
/*****************************************************************************
 * OpenDecoder: probe the decoder and return score
 *****************************************************************************/
static int OpenDecoder( vlc_object_t *p_this )
{
    decoder_t *p_dec = (decoder_t*)p_this;
    decoder_sys_t *p_sys;
    if( p_dec->fmt_in.i_codec != VLC_FOURCC('t','h','e','o') )
    {
        return VLC_EGENERIC;
    }
    /* Allocate the memory needed to store the decoder's structure */
    if( ( p_dec->p_sys = p_sys =
          (decoder_sys_t *)malloc(sizeof(decoder_sys_t)) ) == NULL )
    {
        msg_Err( p_dec, "out of memory" );
        return VLC_EGENERIC;
    }
    p_dec->p_sys->b_packetizer = VLC_FALSE;
    p_sys->i_pts = 0;
    /* Set output properties */
    p_dec->fmt_out.i_cat = VIDEO_ES;
    p_dec->fmt_out.i_codec = VLC_FOURCC('I','4','2','0');
    /* Set callbacks */
    p_dec->pf_decode_video = (picture_t *(*)(decoder_t *, block_t **))
        DecodeBlock;
    p_dec->pf_packetize    = (block_t *(*)(decoder_t *, block_t **))
        DecodeBlock;
    /* Init supporting Theora structures needed in header parsing */
    theora_comment_init( &p_sys->tc );
    theora_info_init( &p_sys->ti );
    p_sys->i_headers = 0;
    return VLC_SUCCESS;
}
static int OpenPacketizer( vlc_object_t *p_this )
{
    decoder_t *p_dec = (decoder_t*)p_this;
    int i_ret = OpenDecoder( p_this );
    if( i_ret == VLC_SUCCESS )
    {
        p_dec->p_sys->b_packetizer = VLC_TRUE;
        p_dec->fmt_out.i_codec = VLC_FOURCC( 't', 'h', 'e', 'o' );
    }
    return i_ret;
}
/****************************************************************************
 * DecodeBlock: the whole thing
 ****************************************************************************
 * This function must be fed with ogg packets.
 ****************************************************************************/
static void *DecodeBlock( decoder_t *p_dec, block_t **pp_block )
{
    decoder_sys_t *p_sys = p_dec->p_sys;
    block_t *p_block;
    ogg_packet oggpacket;
    if( !pp_block || !*pp_block ) return NULL;
    p_block = *pp_block;
    /* Block to Ogg packet */
    oggpacket.packet = p_block->p_buffer;
    oggpacket.bytes = p_block->i_buffer;
    oggpacket.granulepos = p_block->i_dts;
    oggpacket.b_o_s = 0;
    oggpacket.e_o_s = 0;
    oggpacket.packetno = 0;
    /* Check for headers */
    if( p_sys->i_headers == 0 && p_dec->fmt_in.i_extra )
    {
        /* Headers already available as extra data */
        p_sys->i_headers = 3;
    }
    else if( oggpacket.bytes && p_sys->i_headers < 3 )
    {
        /* Backup headers as extra data */
        uint8_t *p_extra;
        p_dec->fmt_in.p_extra =
            realloc( p_dec->fmt_in.p_extra, p_dec->fmt_in.i_extra +
                     oggpacket.bytes + 2 );
        p_extra = p_dec->fmt_in.p_extra + p_dec->fmt_in.i_extra;
        *(p_extra++) = oggpacket.bytes >> 8;
        *(p_extra++) = oggpacket.bytes & 0xFF;
        memcpy( p_extra, oggpacket.packet, oggpacket.bytes );
        p_dec->fmt_in.i_extra += oggpacket.bytes + 2;
        block_Release( *pp_block );
        p_sys->i_headers++;
        return NULL;
    }
    if( p_sys->i_headers == 3 )
    {
        if( ProcessHeaders( p_dec ) != VLC_SUCCESS )
        {
            p_sys->i_headers = 0;
            p_dec->fmt_in.i_extra = 0;
            block_Release( *pp_block );
            return NULL;
        }
        else p_sys->i_headers++;
    }
    return ProcessPacket( p_dec, &oggpacket, pp_block );
}
/*****************************************************************************
 * ProcessHeaders: process Theora headers.
 *****************************************************************************/
static int ProcessHeaders( decoder_t *p_dec )
{
    decoder_sys_t *p_sys = p_dec->p_sys;
    ogg_packet oggpacket;
    uint8_t *p_extra;
    int i_extra;
    if( !p_dec->fmt_in.i_extra ) return VLC_EGENERIC;
    oggpacket.granulepos = -1;
    oggpacket.b_o_s = 1; /* yes this actually is a b_o_s packet :) */
    oggpacket.e_o_s = 0;
    oggpacket.packetno = 0;
    p_extra = p_dec->fmt_in.p_extra;
    i_extra = p_dec->fmt_in.i_extra;
    /* Take care of the initial Vorbis header */
    oggpacket.bytes = *(p_extra++) << 8;
    oggpacket.bytes |= (*(p_extra++) & 0xFF);
    oggpacket.packet = p_extra;
    p_extra += oggpacket.bytes;
    i_extra -= (oggpacket.bytes + 2);
    if( i_extra < 0 )
    {
        msg_Err( p_dec, "header data corrupted");
        return VLC_EGENERIC;
    }
    if( theora_decode_header( &p_sys->ti, &p_sys->tc, &oggpacket ) < 0 )
    {
        msg_Err( p_dec, "This bitstream does not contain Theora video data" );
        return VLC_EGENERIC;
    }
    /* Set output properties */
    p_dec->fmt_out.video.i_width = p_sys->ti.width;
    p_dec->fmt_out.video.i_height = p_sys->ti.height;
    if( p_sys->ti.frame_width && p_sys->ti.frame_height )
    {
        p_dec->fmt_out.video.i_width = p_sys->ti.frame_width;
        p_dec->fmt_out.video.i_height = p_sys->ti.frame_height;
    }
    if( p_sys->ti.aspect_denominator && p_sys->ti.aspect_numerator )
    {
        p_dec->fmt_out.video.i_aspect = ((int64_t)VOUT_ASPECT_FACTOR) *
            ( p_sys->ti.aspect_numerator * p_sys->ti.width ) /
            ( p_sys->ti.aspect_denominator * p_sys->ti.height );
    }
    else
    {
        p_dec->fmt_out.video.i_aspect = VOUT_ASPECT_FACTOR *
            p_sys->ti.frame_width / p_sys->ti.frame_height;
    }
    if( p_sys->ti.fps_numerator > 0 && p_sys->ti.fps_denominator > 0 )
    {
        p_dec->fmt_out.video.i_frame_rate = p_sys->ti.fps_numerator;
        p_dec->fmt_out.video.i_frame_rate_base = p_sys->ti.fps_denominator;
    }
    msg_Dbg( p_dec, "%dx%d %.02f fps video, frame content "
             "is %dx%d with offset (%d,%d)",
             p_sys->ti.width, p_sys->ti.height,
             (double)p_sys->ti.fps_numerator/p_sys->ti.fps_denominator,
             p_sys->ti.frame_width, p_sys->ti.frame_height,
             p_sys->ti.offset_x, p_sys->ti.offset_y );
    /* The next packet in order is the comments header */
    oggpacket.b_o_s = 0;
    oggpacket.bytes = *(p_extra++) << 8;
    oggpacket.bytes |= (*(p_extra++) & 0xFF);
    oggpacket.packet = p_extra;
    p_extra += oggpacket.bytes;
    i_extra -= (oggpacket.bytes + 2);
    if( i_extra < 0 )
    {
        msg_Err( p_dec, "header data corrupted");
        return VLC_EGENERIC;
    }
    /* The next packet in order is the comments header */
    if( theora_decode_header( &p_sys->ti, &p_sys->tc, &oggpacket ) < 0 )
    {
        msg_Err( p_dec, "2nd Theora header is corrupted" );
        return VLC_EGENERIC;
    }
    ParseTheoraComments( p_dec );
    /* The next packet in order is the codebooks header
     * We need to watch out that this packet is not missing as a
     * missing or corrupted header is fatal. */
    oggpacket.bytes = *(p_extra++) << 8;
    oggpacket.bytes |= (*(p_extra++) & 0xFF);
    oggpacket.packet = p_extra;
    i_extra -= (oggpacket.bytes + 2);
    if( i_extra < 0 )
    {
        msg_Err( p_dec, "header data corrupted");
        return VLC_EGENERIC;
    }
    /* The next packet in order is the codebooks header
     * We need to watch out that this packet is not missing as a
     * missing or corrupted header is fatal */
    if( theora_decode_header( &p_sys->ti, &p_sys->tc, &oggpacket ) < 0 )
    {
        msg_Err( p_dec, "3rd Theora header is corrupted" );
        return VLC_EGENERIC;
    }
    if( !p_sys->b_packetizer )
    {
        /* We have all the headers, initialize decoder */
        theora_decode_init( &p_sys->td, &p_sys->ti );
    }
    else
    {
        p_dec->fmt_out.i_extra = p_dec->fmt_in.i_extra;
        p_dec->fmt_out.p_extra =
            realloc( p_dec->fmt_out.p_extra, p_dec->fmt_out.i_extra );
        memcpy( p_dec->fmt_out.p_extra,
                p_dec->fmt_in.p_extra, p_dec->fmt_out.i_extra );
    }
    return VLC_SUCCESS;
}
/*****************************************************************************
 * ProcessPacket: processes a theora packet.
 *****************************************************************************/
static void *ProcessPacket( decoder_t *p_dec, ogg_packet *p_oggpacket,
                            block_t **pp_block )
{
    decoder_sys_t *p_sys = p_dec->p_sys;
    block_t *p_block = *pp_block;
    void *p_buf;
    /* Date management */
    if( p_block->i_pts > 0 && p_block->i_pts != p_sys->i_pts )
    {
        p_sys->i_pts = p_block->i_pts;
    }
    *pp_block = NULL; /* To avoid being fed the same packet again */
    if( p_sys->b_packetizer )
    {
        /* Date management */
        p_block->i_dts = p_block->i_pts = p_sys->i_pts;
        if( p_sys->i_headers >= 3 )
            p_block->i_length = p_sys->i_pts - p_block->i_pts;
        else
            p_block->i_length = 0;
        p_buf = p_block;
    }
    else
    {
        if( p_sys->i_headers >= 3 )
            p_buf = DecodePacket( p_dec, p_oggpacket );
        else
            p_buf = NULL;
        if( p_block ) block_Release( p_block );
    }
    /* Date management */
    p_sys->i_pts += ( I64C(1000000) * p_sys->ti.fps_denominator /
                      p_sys->ti.fps_numerator ); /* 1 frame per packet */
    return p_buf;
}
/*****************************************************************************
 * DecodePacket: decodes a Theora packet.
 *****************************************************************************/
static picture_t *DecodePacket( decoder_t *p_dec, ogg_packet *p_oggpacket )
{
    decoder_sys_t *p_sys = p_dec->p_sys;
    picture_t *p_pic;
    yuv_buffer yuv;
    theora_decode_packetin( &p_sys->td, p_oggpacket );
    /* Decode */
    theora_decode_YUVout( &p_sys->td, &yuv );
    /* Get a new picture */
    p_pic = p_dec->pf_vout_buffer_new( p_dec );
    if( !p_pic ) return NULL;
    theora_CopyPicture( p_dec, p_pic, &yuv );
    p_pic->date = p_sys->i_pts;
    return p_pic;
}
/*****************************************************************************
 * ParseTheoraComments: FIXME should be done in demuxer
 *****************************************************************************/
static void ParseTheoraComments( decoder_t *p_dec )
{
    input_thread_t *p_input = (input_thread_t *)p_dec->p_parent;
    char *psz_name, *psz_value, *psz_comment;
    int i = 0;
    if( p_input->i_object_type != VLC_OBJECT_INPUT ) return;
    while ( i < p_dec->p_sys->tc.comments )
    {
        psz_comment = strdup( p_dec->p_sys->tc.user_comments[i] );
        if( !psz_comment )
        {
            msg_Warn( p_dec, "out of memory" );
            break;
        }
        psz_name = psz_comment;
        psz_value = strchr( psz_comment, '=' );
        if( psz_value )
        {
            *psz_value = '';
            psz_value++;
            input_Control( p_input, INPUT_ADD_INFO, _("Theora comment"),
                           psz_name, psz_value );
        }
        free( psz_comment );
        i++;
    }
}
/*****************************************************************************
 * CloseDecoder: theora decoder destruction
 *****************************************************************************/
static void CloseDecoder( vlc_object_t *p_this )
{
    decoder_t *p_dec = (decoder_t *)p_this;
    decoder_sys_t *p_sys = p_dec->p_sys;
    theora_info_clear( &p_sys->ti );
    theora_comment_clear( &p_sys->tc );
    free( p_sys );
}
/*****************************************************************************
 * theora_CopyPicture: copy a picture from theora internal buffers to a
 *                     picture_t structure.
 *****************************************************************************/
static void theora_CopyPicture( decoder_t *p_dec, picture_t *p_pic,
                                yuv_buffer *yuv )
{
    int i_plane, i_line, i_width, i_dst_stride, i_src_stride;
    int i_src_xoffset, i_src_yoffset;
    uint8_t *p_dst, *p_src;
    for( i_plane = 0; i_plane < p_pic->i_planes; i_plane++ )
    {
        p_dst = p_pic->p[i_plane].p_pixels;
        p_src = i_plane ? (i_plane - 1 ? yuv->v : yuv->u ) : yuv->y;
        i_width = p_pic->p[i_plane].i_visible_pitch;
        i_dst_stride  = p_pic->p[i_plane].i_pitch;
        i_src_stride  = i_plane ? yuv->uv_stride : yuv->y_stride;
        i_src_xoffset = p_dec->p_sys->ti.offset_x;
        i_src_yoffset = p_dec->p_sys->ti.offset_y;
        if( i_plane )
        {
            i_src_xoffset /= 2;
            i_src_yoffset /= 2;
        }
        p_src += (i_src_yoffset * i_src_stride + i_src_yoffset);
        for( i_line = 0; i_line < p_pic->p[i_plane].i_visible_lines; i_line++ )
        {
            p_dec->p_vlc->pf_memcpy( p_dst, p_src, i_width );
            p_src += i_src_stride;
            p_dst += i_dst_stride;
        }
    }
}
/*****************************************************************************
 * encoder_sys_t : theora encoder descriptor
 *****************************************************************************/
struct encoder_sys_t
{
    /*
     * Input properties
     */
    vlc_bool_t b_headers;
    /*
     * Theora properties
     */
    theora_info      ti;                        /* theora bitstream settings */
    theora_comment   tc;                            /* theora comment header */
    theora_state     td;                   /* theora bitstream user comments */
    int i_width, i_height;
};
/*****************************************************************************
 * OpenEncoder: probe the encoder and return score
 *****************************************************************************/
static int OpenEncoder( vlc_object_t *p_this )
{
    encoder_t *p_enc = (encoder_t *)p_this;
    encoder_sys_t *p_sys = p_enc->p_sys;
    ogg_packet header;
    uint8_t *p_extra;
    vlc_value_t val;
    int i_quality, i;
    if( p_enc->fmt_out.i_codec != VLC_FOURCC('t','h','e','o') &&
        !p_enc->b_force )
    {
        return VLC_EGENERIC;
    }
    /* Allocate the memory needed to store the decoder's structure */
    if( ( p_sys = (encoder_sys_t *)malloc(sizeof(encoder_sys_t)) ) == NULL )
    {
        msg_Err( p_enc, "out of memory" );
        return VLC_EGENERIC;
    }
    p_enc->p_sys = p_sys;
    p_enc->pf_encode_video = Encode;
    p_enc->fmt_in.i_codec = VLC_FOURCC('I','4','2','0');
    p_enc->fmt_out.i_codec = VLC_FOURCC('t','h','e','o');
    sout_CfgParse( p_enc, ENC_CFG_PREFIX, ppsz_enc_options, p_enc->p_cfg );
    var_Get( p_enc, ENC_CFG_PREFIX "quality", &val );
    i_quality = val.i_int;
    if( i_quality > 10 ) i_quality = 10;
    if( i_quality < 0 ) i_quality = 0;
    theora_info_init( &p_sys->ti );
    p_sys->ti.width = p_enc->fmt_in.video.i_width;
    p_sys->ti.height = p_enc->fmt_in.video.i_height;
    if( p_sys->ti.width % 16 || p_sys->ti.height % 16 )
    {
        /* Pictures from the transcoder should always have a pitch
         * which is a multiple of 16 */
        p_sys->ti.width = (p_sys->ti.width + 15) >> 4 << 4;
        p_sys->ti.height = (p_sys->ti.height + 15) >> 4 << 4;
        msg_Dbg( p_enc, "padding video from %dx%d to %dx%d",
                 p_enc->fmt_in.video.i_width, p_enc->fmt_in.video.i_height,
                 p_sys->ti.width, p_sys->ti.height );
    }
    p_sys->ti.frame_width = p_enc->fmt_in.video.i_width;
    p_sys->ti.frame_height = p_enc->fmt_in.video.i_height;
    p_sys->ti.offset_x = 0 /*frame_x_offset*/;
    p_sys->ti.offset_y = 0 /*frame_y_offset*/;
    p_sys->i_width = p_sys->ti.width;
    p_sys->i_height = p_sys->ti.height;
    if( !p_enc->fmt_in.video.i_frame_rate ||
        !p_enc->fmt_in.video.i_frame_rate_base )
    {
        p_sys->ti.fps_numerator = 25;
        p_sys->ti.fps_denominator = 1;
    }
    else
    {
        p_sys->ti.fps_numerator = p_enc->fmt_in.video.i_frame_rate;
        p_sys->ti.fps_denominator = p_enc->fmt_in.video.i_frame_rate_base;
    }
    if( p_enc->fmt_in.video.i_aspect )
    {
        int64_t i_num, i_den;
        int i_dst_num, i_dst_den;
        i_num = p_enc->fmt_in.video.i_aspect * (int64_t)p_sys->ti.height;
        i_den = VOUT_ASPECT_FACTOR * p_sys->ti.width;
        vlc_reduce( &i_dst_num, &i_dst_den, i_num, i_den, 0 );
        p_sys->ti.aspect_numerator = i_dst_num;
        p_sys->ti.aspect_denominator = i_dst_den;
    }
    else
    {
        p_sys->ti.aspect_numerator = 4;
        p_sys->ti.aspect_denominator = 3;
    }
    p_sys->ti.target_bitrate = p_enc->fmt_out.i_bitrate;
    p_sys->ti.quality = ((float)i_quality) * 6.3;
    p_sys->ti.dropframes_p = 0;
    p_sys->ti.quick_p = 1;
    p_sys->ti.keyframe_auto_p = 1;
    p_sys->ti.keyframe_frequency = 64;
    p_sys->ti.keyframe_frequency_force = 64;
    p_sys->ti.keyframe_data_target_bitrate = p_enc->fmt_out.i_bitrate * 1.5;
    p_sys->ti.keyframe_auto_threshold = 80;
    p_sys->ti.keyframe_mindistance = 8;
    p_sys->ti.noise_sensitivity = 1;
    theora_encode_init( &p_sys->td, &p_sys->ti );
    theora_info_clear( &p_sys->ti );
    theora_comment_init( &p_sys->tc );
    /* Create and store headers */
    p_enc->fmt_out.i_extra = 3 * 2;
    for( i = 0; i < 3; i++ )
    {
        if( i == 0 ) theora_encode_header( &p_sys->td, &header );
        else if( i == 1 ) theora_encode_comment( &p_sys->tc, &header );
        else if( i == 2 ) theora_encode_tables( &p_sys->td, &header );
        p_enc->fmt_out.p_extra =
            realloc( p_enc->fmt_out.p_extra,
                     p_enc->fmt_out.i_extra + header.bytes );
        p_extra = p_enc->fmt_out.p_extra;
        p_extra += p_enc->fmt_out.i_extra + (i-3)*2;
        p_enc->fmt_out.i_extra += header.bytes;
        *(p_extra++) = header.bytes >> 8;
        *(p_extra++) = header.bytes & 0xFF;
        memcpy( p_extra, header.packet, header.bytes );
    }
    return VLC_SUCCESS;
}
/****************************************************************************
 * Encode: the whole thing
 ****************************************************************************
 * This function spits out ogg packets.
 ****************************************************************************/
static block_t *Encode( encoder_t *p_enc, picture_t *p_pict )
{
    encoder_sys_t *p_sys = p_enc->p_sys;
    ogg_packet oggpacket;
    block_t *p_block;
    yuv_buffer yuv;
    int i;
    /* Sanity check */
    if( p_pict->p[0].i_pitch < (int)p_sys->i_width ||
        p_pict->p[0].i_lines < (int)p_sys->i_height )
    {
        msg_Warn( p_enc, "frame is smaller than encoding size"
                  "(%ix%i->%ix%i) -> dropping frame",
                  p_pict->p[0].i_pitch, p_pict->p[0].i_lines,
                  p_sys->i_width, p_sys->i_height );
        return NULL;
    }
    /* Fill padding */
    if( p_pict->p[0].i_visible_pitch < (int)p_sys->i_width )
    {
        for( i = 0; i < p_sys->i_height; i++ )
        {
            memset( p_pict->p[0].p_pixels + i * p_pict->p[0].i_pitch +
                    p_pict->p[0].i_visible_pitch,
                    *( p_pict->p[0].p_pixels + i * p_pict->p[0].i_pitch +
                       p_pict->p[0].i_visible_pitch - 1 ),
                    p_sys->i_width - p_pict->p[0].i_visible_pitch );
        }
        for( i = 0; i < p_sys->i_height / 2; i++ )
        {
            memset( p_pict->p[1].p_pixels + i * p_pict->p[1].i_pitch +
                    p_pict->p[1].i_visible_pitch,
                    *( p_pict->p[1].p_pixels + i * p_pict->p[1].i_pitch +
                       p_pict->p[1].i_visible_pitch - 1 ),
                    p_sys->i_width / 2 - p_pict->p[1].i_visible_pitch );
            memset( p_pict->p[2].p_pixels + i * p_pict->p[2].i_pitch +
                    p_pict->p[2].i_visible_pitch,
                    *( p_pict->p[2].p_pixels + i * p_pict->p[2].i_pitch +
                       p_pict->p[2].i_visible_pitch - 1 ),
                    p_sys->i_width / 2 - p_pict->p[2].i_visible_pitch );
        }
    }
    if( p_pict->p[0].i_visible_lines < (int)p_sys->i_height )
    {
        for( i = p_pict->p[0].i_visible_lines; i < p_sys->i_height; i++ )
        {
            memset( p_pict->p[0].p_pixels + i * p_pict->p[0].i_pitch, 0,
                    p_sys->i_width );
        }
        for( i = p_pict->p[1].i_visible_lines; i < p_sys->i_height / 2; i++ )
        {
            memset( p_pict->p[1].p_pixels + i * p_pict->p[1].i_pitch, 0x80,
                    p_sys->i_width / 2 );
            memset( p_pict->p[2].p_pixels + i * p_pict->p[2].i_pitch, 0x80,
                    p_sys->i_width / 2 );
        }
    }
    /* Theora is a one-frame-in, one-frame-out system. Submit a frame
     * for compression and pull out the packet. */
    yuv.y_width  = p_sys->i_width;
    yuv.y_height = p_sys->i_height;
    yuv.y_stride = p_pict->p[0].i_pitch;
    yuv.uv_width  = p_sys->i_width / 2;
    yuv.uv_height = p_sys->i_height / 2;
    yuv.uv_stride = p_pict->p[1].i_pitch;
    yuv.y = p_pict->p[0].p_pixels;
    yuv.u = p_pict->p[1].p_pixels;
    yuv.v = p_pict->p[2].p_pixels;
    if( theora_encode_YUVin( &p_sys->td, &yuv ) < 0 )
    {
        msg_Warn( p_enc, "failed encoding a frame" );
        return NULL;
    }
    theora_encode_packetout( &p_sys->td, 0, &oggpacket );
    /* Ogg packet to block */
    p_block = block_New( p_enc, oggpacket.bytes );
    memcpy( p_block->p_buffer, oggpacket.packet, oggpacket.bytes );
    p_block->i_dts = p_block->i_pts = p_pict->date;
    return p_block;
}
/*****************************************************************************
 * CloseEncoder: theora encoder destruction
 *****************************************************************************/
static void CloseEncoder( vlc_object_t *p_this )
{
    encoder_t *p_enc = (encoder_t *)p_this;
    encoder_sys_t *p_sys = p_enc->p_sys;
    theora_info_clear( &p_sys->ti );
    theora_comment_clear( &p_sys->tc );
    free( p_sys );
}

						