path: root/pjmedia/src/pjmedia/avi_player.c

/* $Id$ */
/* 
 * Copyright (C) 2008-2011 Teluu Inc. (http://www.teluu.com)
 *
 * 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  02111-1307  USA 
 */

/**
 * Default file player/writer buffer size.
 */
#include <pjmedia/avi_stream.h>
#include <pjmedia/avi.h>
#include <pjmedia/errno.h>
#include <pjmedia/wave.h>
#include <pj/assert.h>
#include <pj/file_access.h>
#include <pj/file_io.h>
#include <pj/log.h>
#include <pj/pool.h>
#include <pj/string.h>


#if defined(PJMEDIA_HAS_VIDEO) && (PJMEDIA_HAS_VIDEO != 0)


#define THIS_FILE   "avi_player.c"

#define AVIF_MUSTUSEINDEX       0x00000020
#define AVIF_ISINTERLEAVED      0x00000100
#define AVISF_DISABLED          0x00000001
#define AVISF_VIDEO_PALCHANGES  0x00010000

#define AVI_EOF 0xFFEEFFEE

#define COMPARE_TAG(doc_tag, tag) (doc_tag == *((pj_uint32_t *)avi_tags[tag]))

#define SIGNATURE	    PJMEDIA_SIG_PORT_VID_AVI_PLAYER

#define VIDEO_CLOCK_RATE	90000

#if 0
#   define TRACE_(x)	PJ_LOG(4,x)
#else
#   define TRACE_(x)
#endif

#if defined(PJ_IS_BIG_ENDIAN) && PJ_IS_BIG_ENDIAN!=0
    static void data_to_host(void *data, pj_uint8_t bits, unsigned count)
    {
	unsigned i;

        count /= (bits == 32? 4 : 2);

	if (bits == 32) {
	    pj_int32_t *data32 = (pj_int32_t *)data;
	    for (i=0; i<count; ++i)
		data32[i] = pj_swap32(data32[i]);
	} else {
	    pj_int16_t *data16 = (pj_int16_t *)data;
	    for (i=0; i<count; ++i)
		data16[i] = pj_swap16(data16[i]);
	}

    }
    static void data_to_host2(void *data, pj_uint8_t nsizes,
                              pj_uint8_t *sizes)
    {
	unsigned i;
        pj_int8_t *datap = (pj_int8_t *)data;
        for (i = 0; i < nsizes; i++) {
            data_to_host(datap, 32, sizes[i]);
            datap += sizes[i++];
            if (i >= nsizes)
                break;
            data_to_host(datap, 16, sizes[i]);
            datap += sizes[i];
	}
    }
#else
#   define data_to_host(data, bits, count)
#   define data_to_host2(data, nsizes, sizes)
#endif

typedef struct avi_fmt_info
{
    pjmedia_format_id   fmt_id;
    pjmedia_format_id   eff_fmt_id;
} avi_fmt_info;

static avi_fmt_info avi_fmts[] =
{
    {PJMEDIA_FORMAT_MJPEG}, {PJMEDIA_FORMAT_H264},
    {PJMEDIA_FORMAT_UYVY}, {PJMEDIA_FORMAT_YUY2},
    {PJMEDIA_FORMAT_IYUV}, {PJMEDIA_FORMAT_I420},
    {PJMEDIA_FORMAT_DIB}, {PJMEDIA_FORMAT_RGB24},
    {PJMEDIA_FORMAT_RGB32},
    {PJMEDIA_FORMAT_PACK('X','V','I','D'), PJMEDIA_FORMAT_MPEG4},
    {PJMEDIA_FORMAT_PACK('x','v','i','d'), PJMEDIA_FORMAT_MPEG4},
    {PJMEDIA_FORMAT_PACK('D','I','V','X'), PJMEDIA_FORMAT_MPEG4},
    {PJMEDIA_FORMAT_PACK('F','M','P','4'), PJMEDIA_FORMAT_MPEG4},
    {PJMEDIA_FORMAT_PACK('D','X','5','0'), PJMEDIA_FORMAT_MPEG4}
};

struct pjmedia_avi_streams
{
    unsigned        num_streams;
    pjmedia_port  **streams;
};

struct avi_reader_port
{
    pjmedia_port     base;
    unsigned         stream_id;
    unsigned	     options;
    pjmedia_format_id fmt_id;
    unsigned         usec_per_frame;
    pj_uint16_t	     bits_per_sample;
    pj_bool_t	     eof;
    pj_off_t	     fsize;
    pj_off_t	     start_data;
    pj_uint8_t       pad;
    pj_oshandle_t    fd;
    pj_ssize_t       size_left;
    pj_timestamp     next_ts;

    pj_status_t	   (*cb)(pjmedia_port*, void*);
};


static pj_status_t avi_get_frame(pjmedia_port *this_port, 
			         pjmedia_frame *frame);
static pj_status_t avi_on_destroy(pjmedia_port *this_port);

static struct avi_reader_port *create_avi_port(pj_pool_t *pool)
{
    const pj_str_t name = pj_str("file");
    struct avi_reader_port *port;

    port = PJ_POOL_ZALLOC_T(pool, struct avi_reader_port);
    if (!port)
	return NULL;

    /* Put in default values.
     * These will be overriden once the file is read.
     */
    pjmedia_port_info_init(&port->base.info, &name, SIGNATURE, 
			   8000, 1, 16, 80);

    port->fd = (pj_oshandle_t)(pj_ssize_t)-1;
    port->base.get_frame = &avi_get_frame;
    port->base.on_destroy = &avi_on_destroy;

    return port;
}

#define file_read(fd, data, size) file_read2(fd, data, size, 32)
#define file_read2(fd, data, size, bits) file_read3(fd, data, size, bits, NULL)

static pj_status_t file_read3(pj_oshandle_t fd, void *data, pj_ssize_t size,
                              pj_uint16_t bits, pj_ssize_t *psz_read)
{
    pj_ssize_t size_read = size, size_to_read = size;
    pj_status_t status = pj_file_read(fd, data, &size_read);
    if (status != PJ_SUCCESS)
        return status;

    /* Normalize AVI header fields values from little-endian to host
     * byte order.
     */
    if (bits > 0)
        data_to_host(data, bits, size_read);

    if (size_read != size_to_read) {
        if (psz_read)
            *psz_read = size_read;
        return AVI_EOF;
    }

    return status;
}

/*
 * Create AVI player port.
 */
PJ_DEF(pj_status_t)
pjmedia_avi_player_create_streams(pj_pool_t *pool,
                                  const char *filename,
				  unsigned options,
				  pjmedia_avi_streams **p_streams)
{
    pjmedia_avi_hdr avi_hdr;
    struct avi_reader_port *fport[PJMEDIA_AVI_MAX_NUM_STREAMS];
    pj_off_t pos;
    unsigned i, nstr = 0;
    pj_status_t status = PJ_SUCCESS;

    /* Check arguments. */
    PJ_ASSERT_RETURN(pool && filename && p_streams, PJ_EINVAL);

    /* Check the file really exists. */
    if (!pj_file_exists(filename)) {
	return PJ_ENOTFOUND;
    }

    /* Create fport instance. */
    fport[0] = create_avi_port(pool);
    if (!fport[0]) {
	return PJ_ENOMEM;
    }

    /* Get the file size. */
    fport[0]->fsize = pj_file_size(filename);

    /* Size must be more than AVI header size */
    if (fport[0]->fsize <= sizeof(riff_hdr_t) + sizeof(avih_hdr_t) + 
                           sizeof(strl_hdr_t))
    {
	return PJMEDIA_EINVALIMEDIATYPE;
    }

    /* Open file. */
    status = pj_file_open(pool, filename, PJ_O_RDONLY, &fport[0]->fd);
    if (status != PJ_SUCCESS)
	return status;

    /* Read the RIFF + AVIH header. */
    status = file_read(fport[0]->fd, &avi_hdr,
                       sizeof(riff_hdr_t) + sizeof(avih_hdr_t));
    if (status != PJ_SUCCESS)
        goto on_error;

    /* Validate AVI file. */
    if (!COMPARE_TAG(avi_hdr.riff_hdr.riff, PJMEDIA_AVI_RIFF_TAG) ||
	!COMPARE_TAG(avi_hdr.riff_hdr.avi, PJMEDIA_AVI_AVI_TAG) ||
        !COMPARE_TAG(avi_hdr.avih_hdr.list_tag, PJMEDIA_AVI_LIST_TAG) ||
        !COMPARE_TAG(avi_hdr.avih_hdr.hdrl_tag, PJMEDIA_AVI_HDRL_TAG) ||
        !COMPARE_TAG(avi_hdr.avih_hdr.avih, PJMEDIA_AVI_AVIH_TAG))
    {
	status = PJMEDIA_EINVALIMEDIATYPE;
        goto on_error;
    }

    PJ_LOG(5, (THIS_FILE, "The AVI file has %d streams.",
               avi_hdr.avih_hdr.num_streams));

    /* Unsupported AVI format. */
    if (avi_hdr.avih_hdr.num_streams > PJMEDIA_AVI_MAX_NUM_STREAMS) {
        status = PJMEDIA_EAVIUNSUPP;
        goto on_error;
    }

    /** 
     * TODO: Possibly unsupported AVI format.
     * If you encounter this warning, verify whether the avi player
     * is working properly.
     */
    if (avi_hdr.avih_hdr.flags & AVIF_MUSTUSEINDEX ||
        avi_hdr.avih_hdr.pad > 1)
    {
        PJ_LOG(3, (THIS_FILE, "Warning!!! Possibly unsupported AVI format: "
                   "flags:%d, pad:%d", avi_hdr.avih_hdr.flags, 
                   avi_hdr.avih_hdr.pad));
    }

    /* Read the headers of each stream. */
    for (i = 0; i < avi_hdr.avih_hdr.num_streams; i++) {
        pj_size_t elem = 0;
        pj_ssize_t size_to_read;

        /* Read strl header */
        status = file_read(fport[0]->fd, &avi_hdr.strl_hdr[i],
                           sizeof(strl_hdr_t));
        if (status != PJ_SUCCESS)
            goto on_error;
        
        elem = COMPARE_TAG(avi_hdr.strl_hdr[i].data_type, 
                           PJMEDIA_AVI_VIDS_TAG) ? 
               sizeof(strf_video_hdr_t) :
               COMPARE_TAG(avi_hdr.strl_hdr[i].data_type, 
                           PJMEDIA_AVI_AUDS_TAG) ?
               sizeof(strf_audio_hdr_t) : 0;

        /* Read strf header */
        status = file_read2(fport[0]->fd, &avi_hdr.strf_hdr[i],
                            elem, 0);
        if (status != PJ_SUCCESS)
            goto on_error;

        /* Normalize the endian */
        if (elem == sizeof(strf_video_hdr_t))
            data_to_host2(&avi_hdr.strf_hdr[i],
                          sizeof(strf_video_hdr_sizes)/
                          sizeof(strf_video_hdr_sizes[0]),
                          strf_video_hdr_sizes);
        else if (elem == sizeof(strf_audio_hdr_t))
            data_to_host2(&avi_hdr.strf_hdr[i],
                          sizeof(strf_audio_hdr_sizes)/
                          sizeof(strf_audio_hdr_sizes[0]),
                          strf_audio_hdr_sizes);

        /* Skip the remainder of the header */
        size_to_read = avi_hdr.strl_hdr[i].list_sz - (sizeof(strl_hdr_t) -
                       8) - elem;
	status = pj_file_setpos(fport[0]->fd, size_to_read, PJ_SEEK_CUR);
	if (status != PJ_SUCCESS) {
            goto on_error;
	}
    }

    /* Finish reading the AVIH header */
    status = pj_file_setpos(fport[0]->fd, avi_hdr.avih_hdr.list_sz +
                            sizeof(riff_hdr_t) + 8, PJ_SEEK_SET);
    if (status != PJ_SUCCESS) {
        goto on_error;
    }

    /* Skip any JUNK or LIST INFO until we get MOVI tag */
    do {
        pjmedia_avi_subchunk ch;
        int read = 0;

        status = file_read(fport[0]->fd, &ch, sizeof(pjmedia_avi_subchunk));
        if (status != PJ_SUCCESS) {
            goto on_error;
        }

        if (COMPARE_TAG(ch.id, PJMEDIA_AVI_LIST_TAG))
        {
            read = 4;
            status = file_read(fport[0]->fd, &ch, read);
            if (COMPARE_TAG(ch.id, PJMEDIA_AVI_MOVI_TAG))
                break;
        }

        status = pj_file_setpos(fport[0]->fd, ch.len-read, PJ_SEEK_CUR);
        if (status != PJ_SUCCESS) {
            goto on_error;
        }
    } while(1);

    status = pj_file_getpos(fport[0]->fd, &pos);
    if (status != PJ_SUCCESS)
        goto on_error;

    for (i = 0, nstr = 0; i < avi_hdr.avih_hdr.num_streams; i++) {
	pjmedia_format_id fmt_id;

        /* Skip non-audio, non-video, or disabled streams) */
        if ((!COMPARE_TAG(avi_hdr.strl_hdr[i].data_type, 
                          PJMEDIA_AVI_VIDS_TAG) &&
             !COMPARE_TAG(avi_hdr.strl_hdr[i].data_type, 
                          PJMEDIA_AVI_AUDS_TAG)) ||
            avi_hdr.strl_hdr[i].flags & AVISF_DISABLED)
        {
            continue;
        }

        if (COMPARE_TAG(avi_hdr.strl_hdr[i].data_type, 
                        PJMEDIA_AVI_VIDS_TAG))
        {
            int j;

            if (avi_hdr.strl_hdr[i].flags & AVISF_VIDEO_PALCHANGES) {
                PJ_LOG(4, (THIS_FILE, "Unsupported video stream"));
                continue;
            }

            fmt_id = avi_hdr.strl_hdr[i].codec;
            for (j = sizeof(avi_fmts)/sizeof(avi_fmts[0])-1; j >= 0; j--) {
                /* Check supported video formats here */
                if (fmt_id == avi_fmts[j].fmt_id) {
                    if (avi_fmts[j].eff_fmt_id)
                        fmt_id = avi_fmts[j].eff_fmt_id;
                    break;
                }
            }
            
            if (j < 0) {
                PJ_LOG(4, (THIS_FILE, "Unsupported video stream"));
                continue;
            }
        } else {
            /* Check supported audio formats here */
            if ((avi_hdr.strl_hdr[i].codec != PJMEDIA_FORMAT_PCM &&
                 avi_hdr.strl_hdr[i].codec != PJMEDIA_FORMAT_ALAW &&
                 avi_hdr.strl_hdr[i].codec != PJMEDIA_FORMAT_ULAW &&
                 avi_hdr.strl_hdr[i].codec != PJMEDIA_WAVE_FMT_TAG_PCM) ||
                avi_hdr.strf_hdr[i].strf_audio_hdr.bits_per_sample != 16)
            {
                PJ_LOG(4, (THIS_FILE, "Unsupported audio stream"));
                continue;
            }
            /* Normalize format ID */
            fmt_id = avi_hdr.strl_hdr[i].codec;
            if (avi_hdr.strl_hdr[i].codec == PJMEDIA_WAVE_FMT_TAG_PCM)
        	fmt_id = PJMEDIA_FORMAT_PCM;
        }

        if (nstr > 0) {
            /* Create fport instance. */
            fport[nstr] = create_avi_port(pool);
            if (!fport[nstr]) {
	        status = PJ_ENOMEM;
                goto on_error;
            }

            /* Open file. */
            status = pj_file_open(pool, filename, PJ_O_RDONLY,
                                  &fport[nstr]->fd);
            if (status != PJ_SUCCESS)
                goto on_error;

            /* Set the file position */
            status = pj_file_setpos(fport[nstr]->fd, pos, PJ_SEEK_SET);
            if (status != PJ_SUCCESS) {
                goto on_error;
            }
        }

        fport[nstr]->stream_id = i;
        fport[nstr]->fmt_id = fmt_id;

        nstr++;
    }

    if (nstr == 0) {
        status = PJMEDIA_EAVIUNSUPP;
        goto on_error;
    }

    for (i = 0; i < nstr; i++) {
        strl_hdr_t *strl_hdr = &avi_hdr.strl_hdr[fport[i]->stream_id];

        /* Initialize */
        fport[i]->options = options;
        fport[i]->fsize = fport[0]->fsize;
        /* Current file position now points to start of data */
        fport[i]->start_data = pos;
        
        if (COMPARE_TAG(strl_hdr->data_type, PJMEDIA_AVI_VIDS_TAG)) {
            strf_video_hdr_t *strf_hdr =
                &avi_hdr.strf_hdr[fport[i]->stream_id].strf_video_hdr;
            const pjmedia_video_format_info *vfi;

            vfi = pjmedia_get_video_format_info(
                pjmedia_video_format_mgr_instance(),
                strl_hdr->codec);

            fport[i]->bits_per_sample = (vfi ? vfi->bpp : 0);
            fport[i]->usec_per_frame = avi_hdr.avih_hdr.usec_per_frame;
            pjmedia_format_init_video(&fport[i]->base.info.fmt,
                                      fport[i]->fmt_id,
                                      strf_hdr->biWidth,
                                      strf_hdr->biHeight,
                                      strl_hdr->rate,
                                      strl_hdr->scale);
#if 0
            /* The calculation below is wrong. strf_hdr->biSizeImage shows
             * uncompressed size. Looks like we need to go the ugly way to
             * get the bitrage:
             *    http://www.virtualdub.org/blog/pivot/entry.php?id=159
             */
            bps = strf_hdr->biSizeImage * 8 * strl_hdr->rate / strl_hdr->scale;
            if (bps==0) {
        	/* strf_hdr->biSizeImage may be zero for uncompressed RGB */
        	bps = strf_hdr->biWidth * strf_hdr->biHeight *
        		strf_hdr->biBitCount *
        		strl_hdr->rate / strl_hdr->scale;
            }
            fport[i]->base.info.fmt.det.vid.avg_bps = bps;
            fport[i]->base.info.fmt.det.vid.max_bps = bps;
#endif
        } else {
            strf_audio_hdr_t *strf_hdr =
                &avi_hdr.strf_hdr[fport[i]->stream_id].strf_audio_hdr;

            fport[i]->bits_per_sample = strf_hdr->bits_per_sample;
            fport[i]->usec_per_frame = avi_hdr.avih_hdr.usec_per_frame;
            pjmedia_format_init_audio(&fport[i]->base.info.fmt,
                                      fport[i]->fmt_id,
                                      strf_hdr->sample_rate,
                                      strf_hdr->nchannels,
                                      strf_hdr->bits_per_sample,
                                      20000 /* fport[i]->usec_per_frame */,
                                      strf_hdr->bytes_per_sec * 8,
                                      strf_hdr->bytes_per_sec * 8);
        }

        pj_strdup2(pool, &fport[i]->base.info.name, filename);
    }

    /* Done. */
    *p_streams = pj_pool_alloc(pool, sizeof(pjmedia_avi_streams));
    (*p_streams)->num_streams = nstr;
    (*p_streams)->streams = pj_pool_calloc(pool, (*p_streams)->num_streams,
                                           sizeof(pjmedia_port *));
    for (i = 0; i < nstr; i++)
        (*p_streams)->streams[i] = &fport[i]->base;

    PJ_LOG(4,(THIS_FILE, 
	      "AVI file player '%.*s' created with "
	      "%d media ports",
	      (int)fport[0]->base.info.name.slen,
	      fport[0]->base.info.name.ptr,
              (*p_streams)->num_streams));

    return PJ_SUCCESS;

on_error:
    fport[0]->base.on_destroy(&fport[0]->base);
    for (i = 1; i < nstr; i++)
        fport[i]->base.on_destroy(&fport[i]->base);
    if (status == AVI_EOF)
        return PJMEDIA_EINVALIMEDIATYPE;
    return status;
}

PJ_DEF(unsigned)
pjmedia_avi_streams_get_num_streams(pjmedia_avi_streams *streams)
{
    pj_assert(streams);
    return streams->num_streams;
}

PJ_DEF(pjmedia_avi_stream *)
pjmedia_avi_streams_get_stream(pjmedia_avi_streams *streams,
                               unsigned idx)
{
    pj_assert(streams);
    return (idx < streams->num_streams ? streams->streams[idx] : NULL);
}

PJ_DEF(pjmedia_avi_stream *)
pjmedia_avi_streams_get_stream_by_media(pjmedia_avi_streams *streams,
                                        unsigned start_idx,
                                        pjmedia_type media_type)
{
    unsigned i;

    pj_assert(streams);
    for (i = start_idx; i < streams->num_streams; i++)
        if (streams->streams[i]->info.fmt.type == media_type)
            return streams->streams[i];
    return NULL;
}


/*
 * Get the data length, in bytes.
 */
PJ_DEF(pj_ssize_t) pjmedia_avi_stream_get_len(pjmedia_avi_stream *stream)
{
    struct avi_reader_port *fport;

    /* Sanity check */
    PJ_ASSERT_RETURN(stream, -PJ_EINVAL);

    /* Check that this is really a player port */
    PJ_ASSERT_RETURN(stream->info.signature == SIGNATURE, -PJ_EINVALIDOP);

    fport = (struct avi_reader_port*) stream;

    return (pj_ssize_t)(fport->fsize - fport->start_data);
}


/*
 * Register a callback to be called when the file reading has reached the
 * end of file.
 */
PJ_DEF(pj_status_t)
pjmedia_avi_stream_set_eof_cb( pjmedia_avi_stream *stream,
			       void *user_data,
			       pj_status_t (*cb)(pjmedia_avi_stream *stream,
						 void *usr_data))
{
    struct avi_reader_port *fport;

    /* Sanity check */
    PJ_ASSERT_RETURN(stream, -PJ_EINVAL);

    /* Check that this is really a player port */
    PJ_ASSERT_RETURN(stream->info.signature == SIGNATURE, -PJ_EINVALIDOP);

    fport = (struct avi_reader_port*) stream;

    fport->base.port_data.pdata = user_data;
    fport->cb = cb;

    return PJ_SUCCESS;
}


/*
 * Get frame from file.
 */
static pj_status_t avi_get_frame(pjmedia_port *this_port, 
			         pjmedia_frame *frame)
{
    struct avi_reader_port *fport = (struct avi_reader_port*)this_port;
    pj_status_t status;
    pj_ssize_t size_read = 0, size_to_read = 0;

    pj_assert(fport->base.info.signature == SIGNATURE);

    /* We encountered end of file */
    if (fport->eof) {
	pj_status_t status = PJ_SUCCESS;

	PJ_LOG(5,(THIS_FILE, "File port %.*s EOF",
		  (int)fport->base.info.name.slen,
		  fport->base.info.name.ptr));

	/* Call callback, if any */
	if (fport->cb)
	    status = (*fport->cb)(this_port, fport->base.port_data.pdata);

	/* If callback returns non PJ_SUCCESS or 'no loop' is specified,
	 * return immediately (and don't try to access player port since
	 * it might have been destroyed by the callback).
	 */
	if ((status != PJ_SUCCESS) ||
            (fport->options & PJMEDIA_AVI_FILE_NO_LOOP)) 
        {
	    frame->type = PJMEDIA_FRAME_TYPE_NONE;
	    frame->size = 0;
	    return PJ_EEOF;
	}

        /* Rewind file */
	PJ_LOG(5,(THIS_FILE, "File port %.*s rewinding..",
		  (int)fport->base.info.name.slen,
		  fport->base.info.name.ptr));
	fport->eof = PJ_FALSE;
        pj_file_setpos(fport->fd, fport->start_data, PJ_SEEK_SET);
    }

    /* Fill frame buffer. */
    size_to_read = frame->size;
    do {
        pjmedia_avi_subchunk ch = {0, 0};
        char *cid;
        unsigned stream_id;

        /* We need to read data from the file past the chunk boundary */
        if (fport->size_left > 0 && fport->size_left < size_to_read) {
            status = file_read3(fport->fd, frame->buf, fport->size_left,
                                fport->bits_per_sample, &size_read);
            if (status != PJ_SUCCESS)
                goto on_error2;
            size_to_read -= fport->size_left;
            fport->size_left = 0;
        }

        /* Read new chunk data */
        if (fport->size_left == 0) {
            pj_off_t pos;
            pj_file_getpos(fport->fd, &pos);

            /* Data is padded to the nearest WORD boundary */
            if (fport->pad) {
                status = pj_file_setpos(fport->fd, fport->pad, PJ_SEEK_CUR);
                fport->pad = 0;
            }

            status = file_read(fport->fd, &ch, sizeof(pjmedia_avi_subchunk));
            if (status != PJ_SUCCESS) {
                size_read = 0;
                goto on_error2;
            }

            cid = (char *)&ch.id;
            if (cid[0] >= '0' && cid[0] <= '9' &&
                cid[1] >= '0' && cid[1] <= '9') 
            {
                stream_id = (cid[0] - '0') * 10 + (cid[1] - '0');
            } else
                stream_id = 100;
            fport->pad = (pj_uint8_t)ch.len & 1;

            TRACE_((THIS_FILE, "Reading movi data at pos %u (%x), id: %.*s, "
                               "length: %u", (unsigned long)pos,
                               (unsigned long)pos, 4, cid, ch.len));

            /* We are only interested in data with our stream id */
            if (stream_id != fport->stream_id) {
                if (COMPARE_TAG(ch.id, PJMEDIA_AVI_LIST_TAG))
                    PJ_LOG(5, (THIS_FILE, "Unsupported LIST tag found in "
                                          "the movi data."));
                else if (COMPARE_TAG(ch.id, PJMEDIA_AVI_RIFF_TAG)) {
                    PJ_LOG(3, (THIS_FILE, "Unsupported format: multiple "
                           "AVIs in a single file."));
                    status = AVI_EOF;
                    goto on_error2;
                }

                status = pj_file_setpos(fport->fd, ch.len,
                                        PJ_SEEK_CUR);
                continue;
            }
            fport->size_left = ch.len;
        }

        frame->type = (fport->base.info.fmt.type == PJMEDIA_TYPE_VIDEO ?
                       PJMEDIA_FRAME_TYPE_VIDEO : PJMEDIA_FRAME_TYPE_AUDIO);

        if (frame->type == PJMEDIA_FRAME_TYPE_AUDIO) {
            if (size_to_read > fport->size_left)
                size_to_read = fport->size_left;
            status = file_read3(fport->fd, (char *)frame->buf + frame->size -
                                size_to_read, size_to_read,
                                fport->bits_per_sample, &size_read);
            if (status != PJ_SUCCESS)
                goto on_error2;
            fport->size_left -= size_to_read;
        } else {
            pj_assert(frame->size >= ch.len);
            status = file_read3(fport->fd, frame->buf, ch.len,
                                0, &size_read);
            if (status != PJ_SUCCESS)
                goto on_error2;
            frame->size = ch.len;
            fport->size_left = 0;
        }

        break;

    } while(1);

    frame->timestamp.u64 = fport->next_ts.u64;
    if (frame->type == PJMEDIA_FRAME_TYPE_AUDIO) {
	if (fport->usec_per_frame) {
	    fport->next_ts.u64 += (fport->usec_per_frame *
				   fport->base.info.fmt.det.aud.clock_rate /
				   1000000);
	} else {
	    fport->next_ts.u64 += (frame->size *
				   fport->base.info.fmt.det.aud.clock_rate /
				   (fport->base.info.fmt.det.aud.avg_bps / 8));
	}
    } else {
	if (fport->usec_per_frame) {
	    fport->next_ts.u64 += (fport->usec_per_frame * VIDEO_CLOCK_RATE /
				   1000000);
	} else {
	    fport->next_ts.u64 += (frame->size * VIDEO_CLOCK_RATE /
				   (fport->base.info.fmt.det.vid.avg_bps / 8));
	}
    }

    return PJ_SUCCESS;

on_error2:
    if (status == AVI_EOF) {
        size_to_read -= size_read;
        pj_bzero((char *)frame->buf + frame->size - size_to_read,
                 size_to_read);
        fport->eof = PJ_TRUE;

        return PJ_SUCCESS;
    }

    return status;
}

/*
 * Destroy port.
 */
static pj_status_t avi_on_destroy(pjmedia_port *this_port)
{
    struct avi_reader_port *fport = (struct avi_reader_port*) this_port;

    pj_assert(this_port->info.signature == SIGNATURE);

    if (fport->fd != (pj_oshandle_t) (pj_ssize_t)-1)
        pj_file_close(fport->fd);
    return PJ_SUCCESS;
}


#endif /* PJMEDIA_HAS_VIDEO */