gstreamer/gst-libs/gst/vaapi/gstvaapidecoder_jpeg.c

/*
 *  gstvaapidecoder_jpeg.c - JPEG decoder
 *
 *  Copyright (C) 2011-2013 Intel Corporation
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Lesser General Public License
 *  as published by the Free Software Foundation; either version 2.1
 *  of the License, or (at your option) any later version.
 *
 *  This library 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
 *  Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public
 *  License along with this library; if not, write to the Free
 *  Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 *  Boston, MA 02110-1301 USA
 */

/**
 * SECTION:gstvaapidecoder_jpeg
 * @short_description: JPEG decoder
 */

#include "sysdeps.h"
#include <string.h>
#include <gst/codecparsers/gstjpegparser.h>
#include "gstvaapicompat.h"
#include "gstvaapidecoder_jpeg.h"
#include "gstvaapidecoder_objects.h"
#include "gstvaapidecoder_priv.h"
#include "gstvaapidisplay_priv.h"
#include "gstvaapiobject_priv.h"

#ifdef HAVE_VA_VA_DEC_JPEG_H
# include <va/va_dec_jpeg.h>
#endif

#define DEBUG 1
#include "gstvaapidebug.h"

#define GST_VAAPI_DECODER_JPEG_CAST(decoder) \
    ((GstVaapiDecoderJpeg *)(decoder))

typedef struct _GstVaapiDecoderJpegPrivate      GstVaapiDecoderJpegPrivate;
typedef struct _GstVaapiDecoderJpegClass        GstVaapiDecoderJpegClass;

struct _GstVaapiDecoderJpegPrivate {
    GstVaapiProfile             profile;
    guint                       width;
    guint                       height;
    GstVaapiPicture            *current_picture;
    GstJpegFrameHdr             frame_hdr;
    GstJpegHuffmanTables        huf_tables;
    GstJpegQuantTables          quant_tables;
    gboolean                    has_huf_table;
    gboolean                    has_quant_table;
    guint                       mcu_restart;
    guint                       is_opened       : 1;
    guint                       profile_changed : 1;
    guint                       expect_SOI      : 1;
};

/**
 * GstVaapiDecoderJpeg:
 *
 * A decoder based on Jpeg.
 */
struct _GstVaapiDecoderJpeg {
    /*< private >*/
    GstVaapiDecoder             parent_instance;
    GstVaapiDecoderJpegPrivate  priv;
};

/**
 * GstVaapiDecoderJpegClass:
 *
 * A decoder class based on Jpeg.
 */
struct _GstVaapiDecoderJpegClass {
    /*< private >*/
    GstVaapiDecoderClass parent_class;
};

static inline void
unit_set_marker_code(GstVaapiDecoderUnit *unit, GstJpegMarkerCode marker)
{
    unit->parsed_info = GSIZE_TO_POINTER(marker);
}

static inline GstJpegMarkerCode
unit_get_marker_code(GstVaapiDecoderUnit *unit)
{
    return GPOINTER_TO_SIZE(unit->parsed_info);
}

static void
gst_vaapi_decoder_jpeg_close(GstVaapiDecoderJpeg *decoder)
{
    GstVaapiDecoderJpegPrivate * const priv = &decoder->priv;

    gst_vaapi_picture_replace(&priv->current_picture, NULL);

    /* Reset all */
    priv->profile               = GST_VAAPI_PROFILE_JPEG_BASELINE;
    priv->width                 = 0;
    priv->height                = 0;
    priv->is_opened             = FALSE;
    priv->profile_changed       = TRUE;
}

static gboolean
gst_vaapi_decoder_jpeg_open(GstVaapiDecoderJpeg *decoder)
{
    GstVaapiDecoderJpegPrivate * const priv = &decoder->priv;

    gst_vaapi_decoder_jpeg_close(decoder);

    priv->expect_SOI = TRUE;
    return TRUE;
}

static void
gst_vaapi_decoder_jpeg_destroy(GstVaapiDecoder *base_decoder)
{
    GstVaapiDecoderJpeg * const decoder =
        GST_VAAPI_DECODER_JPEG_CAST(base_decoder);

    gst_vaapi_decoder_jpeg_close(decoder);
}

static gboolean
gst_vaapi_decoder_jpeg_create(GstVaapiDecoder *base_decoder)
{
    GstVaapiDecoderJpeg * const decoder =
        GST_VAAPI_DECODER_JPEG_CAST(base_decoder);
    GstVaapiDecoderJpegPrivate * const priv = &decoder->priv;

    priv->profile               = GST_VAAPI_PROFILE_JPEG_BASELINE;
    priv->profile_changed       = TRUE;
    return TRUE;
}

static GstVaapiDecoderStatus
ensure_context(GstVaapiDecoderJpeg *decoder)
{
    GstVaapiDecoderJpegPrivate * const priv = &decoder->priv;
    GstVaapiProfile profiles[2];
    GstVaapiEntrypoint entrypoint = GST_VAAPI_ENTRYPOINT_VLD;
    guint i, n_profiles = 0;
    gboolean reset_context = FALSE;

    if (priv->profile_changed) {
        GST_DEBUG("profile changed");
        priv->profile_changed = FALSE;
        reset_context         = TRUE;

        profiles[n_profiles++] = priv->profile;
        //if (priv->profile == GST_VAAPI_PROFILE_JPEG_EXTENDED)
        //    profiles[n_profiles++] = GST_VAAPI_PROFILE_JPEG_BASELINE;

        for (i = 0; i < n_profiles; i++) {
            if (gst_vaapi_display_has_decoder(GST_VAAPI_DECODER_DISPLAY(decoder),
                                              profiles[i], entrypoint))
                break;
        }
        if (i == n_profiles)
            return GST_VAAPI_DECODER_STATUS_ERROR_UNSUPPORTED_PROFILE;
        priv->profile = profiles[i];
    }

    if (reset_context) {
        GstVaapiContextInfo info;

        info.profile    = priv->profile;
        info.entrypoint = entrypoint;
        info.width      = priv->width;
        info.height     = priv->height;
        info.ref_frames = 2;
        reset_context   = gst_vaapi_decoder_ensure_context(
            GST_VAAPI_DECODER(decoder),
            &info
        );
        if (!reset_context)
            return GST_VAAPI_DECODER_STATUS_ERROR_UNKNOWN;
    }
    return GST_VAAPI_DECODER_STATUS_SUCCESS;
}

static GstVaapiDecoderStatus
decode_current_picture(GstVaapiDecoderJpeg *decoder)
{
    GstVaapiDecoderJpegPrivate * const priv = &decoder->priv;
    GstVaapiPicture * const picture = priv->current_picture;

    if (!picture)
        return GST_VAAPI_DECODER_STATUS_SUCCESS;

    if (!gst_vaapi_picture_decode(picture))
        goto error;
    if (!gst_vaapi_picture_output(picture))
        goto error;
    gst_vaapi_picture_replace(&priv->current_picture, NULL);
    return GST_VAAPI_DECODER_STATUS_SUCCESS;

error:
    gst_vaapi_picture_replace(&priv->current_picture, NULL);
    return GST_VAAPI_DECODER_STATUS_ERROR_UNKNOWN;
}

static gboolean
fill_picture(
    GstVaapiDecoderJpeg *decoder, 
    GstVaapiPicture     *picture,
    GstJpegFrameHdr     *frame_hdr
)
{
    VAPictureParameterBufferJPEGBaseline * const pic_param = picture->param;
    guint i;

    memset(pic_param, 0, sizeof(VAPictureParameterBufferJPEGBaseline));
    pic_param->picture_width    = frame_hdr->width;
    pic_param->picture_height   = frame_hdr->height;

    pic_param->num_components   = frame_hdr->num_components;
    if (frame_hdr->num_components > 4)
        return FALSE;
    for (i = 0; i < pic_param->num_components; i++) {
        pic_param->components[i].component_id =
            frame_hdr->components[i].identifier;
        pic_param->components[i].h_sampling_factor =
            frame_hdr->components[i].horizontal_factor;
        pic_param->components[i].v_sampling_factor =
            frame_hdr->components[i].vertical_factor;
        pic_param->components[i].quantiser_table_selector =
            frame_hdr->components[i].quant_table_selector;
    }
    return TRUE;
}

static GstVaapiDecoderStatus
fill_quantization_table(GstVaapiDecoderJpeg *decoder, GstVaapiPicture *picture)
{
    GstVaapiDecoderJpegPrivate * const priv = &decoder->priv;
    VAIQMatrixBufferJPEGBaseline *iq_matrix;
    guint i, j, num_tables;

    if (!priv->has_quant_table)
        gst_jpeg_get_default_quantization_tables(&priv->quant_tables);
    
    picture->iq_matrix = GST_VAAPI_IQ_MATRIX_NEW(JPEGBaseline, decoder);
    if (!picture->iq_matrix) {
        GST_ERROR("failed to allocate quantiser table");
        return GST_VAAPI_DECODER_STATUS_ERROR_ALLOCATION_FAILED;
    }
    iq_matrix = picture->iq_matrix->param;

    num_tables = MIN(G_N_ELEMENTS(iq_matrix->quantiser_table),
                     GST_JPEG_MAX_QUANT_ELEMENTS);

    for (i = 0; i < num_tables; i++) {
        GstJpegQuantTable * const quant_table =
            &priv->quant_tables.quant_tables[i];

        iq_matrix->load_quantiser_table[i] = quant_table->valid;
        if (!iq_matrix->load_quantiser_table[i])
            continue;

        if (quant_table->quant_precision != 0) {
            // Only Baseline profile is supported, thus 8-bit Qk values
            GST_ERROR("unsupported quantization table element precision");
            return GST_VAAPI_DECODER_STATUS_ERROR_UNSUPPORTED_CHROMA_FORMAT;
        }

        for (j = 0; j < GST_JPEG_MAX_QUANT_ELEMENTS; j++)
            iq_matrix->quantiser_table[i][j] = quant_table->quant_table[j];
        iq_matrix->load_quantiser_table[i] = 1;
        quant_table->valid = FALSE;
    }
    return GST_VAAPI_DECODER_STATUS_SUCCESS;
}

static GstVaapiDecoderStatus
fill_huffman_table(GstVaapiDecoderJpeg *decoder, GstVaapiPicture *picture)
{
    GstVaapiDecoderJpegPrivate * const priv = &decoder->priv;
    GstJpegHuffmanTables * const huf_tables = &priv->huf_tables;
    VAHuffmanTableBufferJPEGBaseline *huffman_table;
    guint i, num_tables;

    if (!priv->has_huf_table)
        gst_jpeg_get_default_huffman_tables(&priv->huf_tables);
    
    picture->huf_table = GST_VAAPI_HUFFMAN_TABLE_NEW(JPEGBaseline, decoder);
    if (!picture->huf_table) {
        GST_ERROR("failed to allocate Huffman tables");
        return GST_VAAPI_DECODER_STATUS_ERROR_ALLOCATION_FAILED;
    }
    huffman_table = picture->huf_table->param;

    num_tables = MIN(G_N_ELEMENTS(huffman_table->huffman_table),
                     GST_JPEG_MAX_SCAN_COMPONENTS);

    for (i = 0; i < num_tables; i++) {
        huffman_table->load_huffman_table[i] =
            huf_tables->dc_tables[i].valid && huf_tables->ac_tables[i].valid;
        if (!huffman_table->load_huffman_table[i])
            continue;

        memcpy(huffman_table->huffman_table[i].num_dc_codes,
               huf_tables->dc_tables[i].huf_bits,
               sizeof(huffman_table->huffman_table[i].num_dc_codes));
        memcpy(huffman_table->huffman_table[i].dc_values,
               huf_tables->dc_tables[i].huf_values,
               sizeof(huffman_table->huffman_table[i].dc_values));
        memcpy(huffman_table->huffman_table[i].num_ac_codes,
               huf_tables->ac_tables[i].huf_bits,
               sizeof(huffman_table->huffman_table[i].num_ac_codes));
        memcpy(huffman_table->huffman_table[i].ac_values,
               huf_tables->ac_tables[i].huf_values,
               sizeof(huffman_table->huffman_table[i].ac_values));
        memset(huffman_table->huffman_table[i].pad,
               0,
               sizeof(huffman_table->huffman_table[i].pad));
    }
    return GST_VAAPI_DECODER_STATUS_SUCCESS;
}

static guint
get_max_horizontal_samples(GstJpegFrameHdr *frame_hdr)
{
    guint i, max_factor = 0;

    for (i = 0; i < frame_hdr->num_components; i++) {
        if (frame_hdr->components[i].horizontal_factor > max_factor)
            max_factor = frame_hdr->components[i].horizontal_factor;
    }
    return max_factor;
}

static guint
get_max_vertical_samples(GstJpegFrameHdr *frame_hdr)
{
    guint i, max_factor = 0;

    for (i = 0; i < frame_hdr->num_components; i++) {
        if (frame_hdr->components[i].vertical_factor > max_factor)
            max_factor = frame_hdr->components[i].vertical_factor;
    }
    return max_factor;
}

static GstVaapiDecoderStatus
decode_picture(GstVaapiDecoderJpeg *decoder, GstJpegMarkerSegment *seg,
    const guchar *buf)
{
    GstVaapiDecoderJpegPrivate * const priv = &decoder->priv;
    GstJpegFrameHdr * const frame_hdr = &priv->frame_hdr;

    switch (seg->marker) {
    case GST_JPEG_MARKER_SOF_MIN:
        priv->profile = GST_VAAPI_PROFILE_JPEG_BASELINE;
        break;
    default:
        GST_ERROR("unsupported profile %d", seg->marker);
        return GST_VAAPI_DECODER_STATUS_ERROR_UNSUPPORTED_PROFILE;
    }

    memset(frame_hdr, 0, sizeof(*frame_hdr));
    if (!gst_jpeg_parse_frame_hdr(frame_hdr, buf + seg->offset, seg->size, 0)) {
        GST_ERROR("failed to parse image");
        return GST_VAAPI_DECODER_STATUS_ERROR_BITSTREAM_PARSER;
    }
    priv->height = frame_hdr->height;
    priv->width  = frame_hdr->width;
    return GST_VAAPI_DECODER_STATUS_SUCCESS;
}

static GstVaapiDecoderStatus
decode_huffman_table(
    GstVaapiDecoderJpeg *decoder,
    const guchar        *buf,
    guint                buf_size
)
{
    GstVaapiDecoderJpegPrivate * const priv = &decoder->priv;

    if (!gst_jpeg_parse_huffman_table(&priv->huf_tables, buf, buf_size, 0)) {
        GST_ERROR("failed to parse Huffman table");
        return GST_VAAPI_DECODER_STATUS_ERROR_BITSTREAM_PARSER;
    }
    priv->has_huf_table = TRUE;
    return GST_VAAPI_DECODER_STATUS_SUCCESS;
}

static GstVaapiDecoderStatus
decode_quant_table(
    GstVaapiDecoderJpeg *decoder,
    const guchar        *buf,
    guint                buf_size
)
{
    GstVaapiDecoderJpegPrivate * const priv = &decoder->priv;

    if (!gst_jpeg_parse_quant_table(&priv->quant_tables, buf, buf_size, 0)) {
        GST_ERROR("failed to parse quantization table");
        return GST_VAAPI_DECODER_STATUS_ERROR_BITSTREAM_PARSER;
    }
    priv->has_quant_table = TRUE;
    return GST_VAAPI_DECODER_STATUS_SUCCESS;
}

static GstVaapiDecoderStatus
decode_restart_interval(
    GstVaapiDecoderJpeg *decoder,
    const guchar        *buf,
    guint                buf_size
)
{
    GstVaapiDecoderJpegPrivate * const priv = &decoder->priv;

    if (!gst_jpeg_parse_restart_interval(&priv->mcu_restart, buf, buf_size, 0)) {
        GST_ERROR("failed to parse restart interval");
        return GST_VAAPI_DECODER_STATUS_ERROR_BITSTREAM_PARSER;
    }
    return GST_VAAPI_DECODER_STATUS_SUCCESS;
}

static GstVaapiDecoderStatus
decode_scan(GstVaapiDecoderJpeg *decoder, GstJpegMarkerSegment *seg,
    const guchar *buf)
{
    GstVaapiDecoderJpegPrivate * const priv = &decoder->priv;
    GstVaapiPicture * const picture = priv->current_picture;
    GstVaapiSlice *slice;
    VASliceParameterBufferJPEGBaseline *slice_param;
    GstJpegScanHdr scan_hdr;
    guint scan_hdr_size, scan_data_size;
    guint i, total_h_samples, total_v_samples;

    scan_hdr_size = (buf[seg->offset] << 8) | buf[seg->offset + 1];
    scan_data_size = seg->size - scan_hdr_size;

    memset(&scan_hdr, 0, sizeof(scan_hdr));
    if (!gst_jpeg_parse_scan_hdr(&scan_hdr, buf + seg->offset, seg->size, 0)) {
        GST_ERROR("failed to parse scan header");
        return GST_VAAPI_DECODER_STATUS_ERROR_BITSTREAM_PARSER;
    }

    slice = GST_VAAPI_SLICE_NEW(JPEGBaseline, decoder,
        buf + seg->offset + scan_hdr_size, scan_data_size);
    if (!slice) {
        GST_ERROR("failed to allocate slice");
        return GST_VAAPI_DECODER_STATUS_ERROR_ALLOCATION_FAILED;
    }
    gst_vaapi_picture_add_slice(picture, slice);

    slice_param = slice->param;
    slice_param->num_components = scan_hdr.num_components;
    for (i = 0; i < scan_hdr.num_components; i++) {
        slice_param->components[i].component_selector =
            scan_hdr.components[i].component_selector;
        slice_param->components[i].dc_table_selector =
            scan_hdr.components[i].dc_selector;
        slice_param->components[i].ac_table_selector =
            scan_hdr.components[i].ac_selector;
    }
    slice_param->restart_interval = priv->mcu_restart;
    if (scan_hdr.num_components == 1) { /*non-interleaved*/
        slice_param->slice_horizontal_position = 0;
        slice_param->slice_vertical_position = 0;
        /* Y mcu numbers*/
        if (slice_param->components[0].component_selector == priv->frame_hdr.components[0].identifier) {
            slice_param->num_mcus = (priv->frame_hdr.width/8)*(priv->frame_hdr.height/8);
        } else { /*Cr, Cb mcu numbers*/
            slice_param->num_mcus = (priv->frame_hdr.width/16)*(priv->frame_hdr.height/16);
        }
    } else { /* interleaved */
        slice_param->slice_horizontal_position = 0;
        slice_param->slice_vertical_position = 0;
        total_v_samples = get_max_vertical_samples(&priv->frame_hdr);
        total_h_samples = get_max_horizontal_samples(&priv->frame_hdr);
        slice_param->num_mcus = ((priv->frame_hdr.width + total_h_samples*8 - 1)/(total_h_samples*8)) *
                                ((priv->frame_hdr.height + total_v_samples*8 -1)/(total_v_samples*8));
    }
    return GST_VAAPI_DECODER_STATUS_SUCCESS;
}

static GstVaapiDecoderStatus
decode_segment(GstVaapiDecoderJpeg *decoder, GstJpegMarkerSegment *seg,
    const guchar *buf)
{
    GstVaapiDecoderJpegPrivate * const priv = &decoder->priv;
    GstVaapiDecoderStatus status;

    // Decode segment
    status = GST_VAAPI_DECODER_STATUS_SUCCESS;
    switch (seg->marker) {
    case GST_JPEG_MARKER_SOI:
        priv->has_quant_table = FALSE;
        priv->has_huf_table = FALSE;
        priv->mcu_restart = 0;
        break;
    case GST_JPEG_MARKER_DAC:
        GST_ERROR("unsupported arithmetic coding mode");
        status = GST_VAAPI_DECODER_STATUS_ERROR_UNSUPPORTED_PROFILE;
        break;
    case GST_JPEG_MARKER_DHT:
        status = decode_huffman_table(decoder, buf + seg->offset, seg->size);
        break;
    case GST_JPEG_MARKER_DQT:
        status = decode_quant_table(decoder, buf + seg->offset, seg->size);
        break;
    case GST_JPEG_MARKER_DRI:
        status = decode_restart_interval(decoder, buf + seg->offset, seg->size);
        break;
    case GST_JPEG_MARKER_SOS:
        status = decode_scan(decoder, seg, buf);
        break;
    default:
        // SOFn segments
        if (seg->marker >= GST_JPEG_MARKER_SOF_MIN &&
            seg->marker <= GST_JPEG_MARKER_SOF_MAX)
            status = decode_picture(decoder, seg, buf);
        break;
    }
    return status;
}

static GstVaapiDecoderStatus
ensure_decoder(GstVaapiDecoderJpeg *decoder)
{
    GstVaapiDecoderJpegPrivate * const priv = &decoder->priv;

    if (!priv->is_opened) {
        priv->is_opened = gst_vaapi_decoder_jpeg_open(decoder);
        if (!priv->is_opened)
            return GST_VAAPI_DECODER_STATUS_ERROR_UNSUPPORTED_CODEC;
    }
    return GST_VAAPI_DECODER_STATUS_SUCCESS;
}

static gboolean
is_scan_complete(GstJpegMarkerCode marker)
{
    // Scan is assumed to be complete when the new segment is not RSTi
    return marker < GST_JPEG_MARKER_RST_MIN || marker > GST_JPEG_MARKER_RST_MAX;
}

static GstVaapiDecoderStatus
gst_vaapi_decoder_jpeg_parse(GstVaapiDecoder *base_decoder,
    GstAdapter *adapter, gboolean at_eos, GstVaapiDecoderUnit *unit)
{
    GstVaapiDecoderJpeg * const decoder =
        GST_VAAPI_DECODER_JPEG_CAST(base_decoder);
    GstVaapiDecoderJpegPrivate * const priv = &decoder->priv;
    GstVaapiParserState * const ps = GST_VAAPI_PARSER_STATE(base_decoder);
    GstVaapiDecoderStatus status;
    GstJpegMarkerCode marker;
    GstJpegMarkerSegment seg;
    const guchar *buf;
    guint buf_size, flags;
    gint ofs1, ofs2;

    status = ensure_decoder(decoder);
    if (status != GST_VAAPI_DECODER_STATUS_SUCCESS)
        return status;

    /* Expect at least 2 bytes for the marker */
    buf_size = gst_adapter_available(adapter);
    if (buf_size < 2)
        return GST_VAAPI_DECODER_STATUS_ERROR_NO_DATA;

    buf = gst_adapter_map(adapter, buf_size);
    if (!buf)
        return GST_VAAPI_DECODER_STATUS_ERROR_NO_DATA;

    ofs1 = ps->input_offset1 - 2;
    if (ofs1 < 0)
        ofs1 = 0;

    for (;;) {
        // Skip any garbage until we reach SOI, if needed
        if (!gst_jpeg_parse(&seg, buf, buf_size, ofs1)) {
            gst_adapter_unmap(adapter);
            ps->input_offset1 = buf_size;
            return GST_VAAPI_DECODER_STATUS_ERROR_NO_DATA;
        }
        ofs1 = seg.offset;

        marker = seg.marker;
        if (priv->expect_SOI && marker != GST_JPEG_MARKER_SOI)
            continue;
        if (marker == GST_JPEG_MARKER_SOS) {
            ofs2 = ps->input_offset2 - 2;
            if (ofs2 < ofs1 + seg.size)
                ofs2 = ofs1 + seg.size;

            // Parse the whole scan + ECSs, including RSTi
            for (;;) {
                if (!gst_jpeg_parse(&seg, buf, buf_size, ofs2)) {
                    gst_adapter_unmap(adapter);
                    ps->input_offset1 = ofs1;
                    ps->input_offset2 = buf_size;
                    return GST_VAAPI_DECODER_STATUS_ERROR_NO_DATA;
                }

                if (is_scan_complete(seg.marker))
                    break;
                ofs2 = seg.offset + seg.size;
            }
            ofs2 = seg.offset - 2;
        }
        else {
            // Check that the whole segment is actually available (in buffer)
            ofs2 = ofs1 + seg.size;
            if (ofs2 > buf_size) {
                gst_adapter_unmap(adapter);
                ps->input_offset1 = ofs1;
                return GST_VAAPI_DECODER_STATUS_ERROR_NO_DATA;
            }
        }
        break;
    }
    gst_adapter_unmap(adapter);

    unit->size = ofs2 - ofs1;
    unit_set_marker_code(unit, marker);
    gst_adapter_flush(adapter, ofs1);
    ps->input_offset1 = 2;
    ps->input_offset2 = 2;

    flags = 0;
    switch (marker) {
    case GST_JPEG_MARKER_SOI:
        flags |= GST_VAAPI_DECODER_UNIT_FLAG_FRAME_START;
        priv->expect_SOI = FALSE;
        break;
    case GST_JPEG_MARKER_EOI:
        flags |= GST_VAAPI_DECODER_UNIT_FLAG_FRAME_END;
        priv->expect_SOI = TRUE;
        break;
    case GST_JPEG_MARKER_SOS:
        flags |= GST_VAAPI_DECODER_UNIT_FLAG_SLICE;
        break;
    case GST_JPEG_MARKER_DNL:
        flags |= GST_VAAPI_DECODER_UNIT_FLAG_SLICE;
        break;
    case GST_JPEG_MARKER_COM:
        flags |= GST_VAAPI_DECODER_UNIT_FLAG_SKIP;
        break;
    default:
        /* Application segments */
        if (marker >= GST_JPEG_MARKER_APP_MIN &&
            marker <= GST_JPEG_MARKER_APP_MAX)
            flags |= GST_VAAPI_DECODER_UNIT_FLAG_SKIP;

        /* Reserved */
        else if (marker >= 0x02 && marker <= 0xbf)
            flags |= GST_VAAPI_DECODER_UNIT_FLAG_SKIP;
        break;
    }
    GST_VAAPI_DECODER_UNIT_FLAG_SET(unit, flags);
    return GST_VAAPI_DECODER_STATUS_SUCCESS;
}

static GstVaapiDecoderStatus
gst_vaapi_decoder_jpeg_decode(GstVaapiDecoder *base_decoder,
    GstVaapiDecoderUnit *unit)
{
    GstVaapiDecoderJpeg * const decoder =
        GST_VAAPI_DECODER_JPEG_CAST(base_decoder);
    GstVaapiDecoderStatus status;
    GstJpegMarkerSegment seg;
    GstBuffer * const buffer =
        GST_VAAPI_DECODER_CODEC_FRAME(decoder)->input_buffer;
    GstMapInfo map_info;

    status = ensure_decoder(decoder);
    if (status != GST_VAAPI_DECODER_STATUS_SUCCESS)
        return status;

    if (!gst_buffer_map(buffer, &map_info, GST_MAP_READ)) {
        GST_ERROR("failed to map buffer");
        return GST_VAAPI_DECODER_STATUS_ERROR_UNKNOWN;
    }

    seg.marker = unit_get_marker_code(unit);
    seg.offset = unit->offset;
    seg.size = unit->size;

    status = decode_segment(decoder, &seg, map_info.data);
    gst_buffer_unmap(buffer, &map_info);
    if (status != GST_VAAPI_DECODER_STATUS_SUCCESS)
        return status;
    return GST_VAAPI_DECODER_STATUS_SUCCESS;
}

static GstVaapiDecoderStatus
gst_vaapi_decoder_jpeg_start_frame(GstVaapiDecoder *base_decoder,
    GstVaapiDecoderUnit *base_unit)
{
    GstVaapiDecoderJpeg * const decoder =
        GST_VAAPI_DECODER_JPEG_CAST(base_decoder);
    GstVaapiDecoderJpegPrivate * const priv = &decoder->priv;
    GstVaapiPicture *picture;
    GstVaapiDecoderStatus status;

    status = ensure_context(decoder);
    if (status != GST_VAAPI_DECODER_STATUS_SUCCESS) {
        GST_ERROR("failed to reset context");
        return status;
    }

    picture = GST_VAAPI_PICTURE_NEW(JPEGBaseline, decoder);
    if (!picture) {
        GST_ERROR("failed to allocate picture");
        return GST_VAAPI_DECODER_STATUS_ERROR_ALLOCATION_FAILED;
    }
    gst_vaapi_picture_replace(&priv->current_picture, picture);
    gst_vaapi_picture_unref(picture);

    if (!fill_picture(decoder, picture, &priv->frame_hdr))
        return GST_VAAPI_DECODER_STATUS_ERROR_UNKNOWN;

    status = fill_quantization_table(decoder, picture);
    if (status != GST_VAAPI_DECODER_STATUS_SUCCESS)
        return status;

    status = fill_huffman_table(decoder, picture);
    if (status != GST_VAAPI_DECODER_STATUS_SUCCESS)
        return status;

    /* Update presentation time */
    picture->pts = GST_VAAPI_DECODER_CODEC_FRAME(decoder)->pts;
    return GST_VAAPI_DECODER_STATUS_SUCCESS;
}

static GstVaapiDecoderStatus
gst_vaapi_decoder_jpeg_end_frame(GstVaapiDecoder *base_decoder)
{
    GstVaapiDecoderJpeg * const decoder =
        GST_VAAPI_DECODER_JPEG_CAST(base_decoder);

    return decode_current_picture(decoder);
}

static void
gst_vaapi_decoder_jpeg_class_init(GstVaapiDecoderJpegClass *klass)
{
    GstVaapiMiniObjectClass * const object_class =
        GST_VAAPI_MINI_OBJECT_CLASS(klass);
    GstVaapiDecoderClass * const decoder_class = GST_VAAPI_DECODER_CLASS(klass);

    object_class->size          = sizeof(GstVaapiDecoderJpeg);
    object_class->finalize      = (GDestroyNotify)gst_vaapi_decoder_finalize;

    decoder_class->create       = gst_vaapi_decoder_jpeg_create;
    decoder_class->destroy      = gst_vaapi_decoder_jpeg_destroy;
    decoder_class->parse        = gst_vaapi_decoder_jpeg_parse;
    decoder_class->decode       = gst_vaapi_decoder_jpeg_decode;
    decoder_class->start_frame  = gst_vaapi_decoder_jpeg_start_frame;
    decoder_class->end_frame    = gst_vaapi_decoder_jpeg_end_frame;
}

static inline const GstVaapiDecoderClass *
gst_vaapi_decoder_jpeg_class(void)
{
    static GstVaapiDecoderJpegClass g_class;
    static gsize g_class_init = FALSE;

    if (g_once_init_enter(&g_class_init)) {
        gst_vaapi_decoder_jpeg_class_init(&g_class);
        g_once_init_leave(&g_class_init, TRUE);
    }
    return GST_VAAPI_DECODER_CLASS(&g_class);
}

/**
 * gst_vaapi_decoder_jpeg_new:
 * @display: a #GstVaapiDisplay
 * @caps: a #GstCaps holding codec information
 *
 * Creates a new #GstVaapiDecoder for JPEG decoding.  The @caps can
 * hold extra information like codec-data and pictured coded size.
 *
 * Return value: the newly allocated #GstVaapiDecoder object
 */
GstVaapiDecoder *
gst_vaapi_decoder_jpeg_new(GstVaapiDisplay *display, GstCaps *caps)
{
    return gst_vaapi_decoder_new(gst_vaapi_decoder_jpeg_class(), display, caps);
}