codec: jpeg encoder implemented

This patch implements jpeg encoder using libjpeg.
Signed-off-by: Rafaël Carré <funman@videolan.org>

modules/codec/jpeg.c

@@ -45,6 +45,12 @@
                                                             \
 /**@}*/                                                     \
 
+#define ENC_CFG_PREFIX "sout-jpeg-"
+#define ENC_QUALITY_TEXT N_("Quality level")
+#define ENC_QUALITY_LONGTEXT N_("Quality level " \
+    "for encoding (this can enlarge or reduce output image size).")
+
+
 /*
  * jpeg common descriptor
  */
@@ -70,16 +76,50 @@ static void CloseDecoder(vlc_object_t *);
 
 static picture_t *DecodeBlock(decoder_t *, block_t **);
 
+/*
+ * jpeg encoder descriptor
+ */
+struct encoder_sys_t
+{
+    JPEG_SYS_COMMON_MEMBERS
+
+    struct jpeg_compress_struct p_jpeg;
+
+    int i_blocksize;
+    int i_quality;
+};
+
+static const char * const ppsz_enc_options[] = {
+    "quality",
+    NULL
+};
+
+static int  OpenEncoder(vlc_object_t *);
+static void CloseEncoder(vlc_object_t *);
+
+static block_t *EncodeBlock(encoder_t *, picture_t *);
+
 /*
  * Module descriptor
  */
 vlc_module_begin()
     set_category(CAT_INPUT)
     set_subcategory(SUBCAT_INPUT_VCODEC)
+    /* decoder main module */
     set_description(N_("JPEG image decoder"))
     set_capability("decoder", 1000)
     set_callbacks(OpenDecoder, CloseDecoder)
     add_shortcut("jpeg")
+
+    /* encoder submodule */
+    add_submodule()
+    add_shortcut("jpeg")
+    set_section(N_("Encoding"), NULL)
+    set_description(N_("JPEG image encoder"))
+    set_capability("encoder", 1000)
+    set_callbacks(OpenEncoder, CloseEncoder)
+    add_integer_with_range(ENC_CFG_PREFIX "quality", 95, 0, 100,
+                           ENC_QUALITY_TEXT, ENC_QUALITY_LONGTEXT, true)
 vlc_module_end()
 
 
@@ -246,3 +286,145 @@ static void CloseDecoder(vlc_object_t *p_this)
 
     free(p_sys);
 }
+
+/*
+ * Probe the encoder and return score
+ */
+static int OpenEncoder(vlc_object_t *p_this)
+{
+    encoder_t *p_enc = (encoder_t *)p_this;
+
+    config_ChainParse(p_enc, ENC_CFG_PREFIX, ppsz_enc_options, p_enc->p_cfg);
+
+    if (p_enc->fmt_out.i_codec != VLC_CODEC_JPEG)
+    {
+        return VLC_EGENERIC;
+    }
+
+    /* Allocate the memory needed to store encoder's structure */
+    encoder_sys_t *p_sys = malloc(sizeof(encoder_sys_t));
+    if (p_sys == NULL)
+    {
+        return VLC_ENOMEM;
+    }
+
+    p_enc->p_sys = p_sys;
+
+    p_sys->p_obj = p_this;
+
+    p_sys->p_jpeg.err = jpeg_std_error(&p_sys->err);
+    p_sys->err.error_exit = user_error_exit;
+    p_sys->err.output_message = user_error_message;
+
+    p_sys->i_quality = var_GetInteger(p_enc, ENC_CFG_PREFIX "quality");
+    p_sys->i_blocksize = 3 * p_enc->fmt_in.video.i_visible_width * p_enc->fmt_in.video.i_visible_height;
+
+    p_enc->fmt_in.i_codec = VLC_CODEC_J420;
+    p_enc->pf_encode_video = EncodeBlock;
+
+    return VLC_SUCCESS;
+}
+
+/*
+ * EncodeBlock
+ */
+static block_t *EncodeBlock(encoder_t *p_enc, picture_t *p_pic)
+{
+    encoder_sys_t *p_sys = p_enc->p_sys;
+
+    block_t *p_block = block_Alloc(p_sys->i_blocksize);
+    if (p_block == NULL)
+    {
+        return NULL;
+    }
+
+    JSAMPIMAGE p_row_pointers = NULL;
+
+    /* libjpeg longjmp's there in case of error */
+    if (setjmp(p_sys->setjmp_buffer))
+    {
+        goto error;
+    }
+
+    jpeg_create_compress(&p_sys->p_jpeg);
+    jpeg_mem_dest(&p_sys->p_jpeg, &p_block->p_buffer, &p_block->i_buffer);
+
+    p_sys->p_jpeg.image_width = p_enc->fmt_in.video.i_visible_width;
+    p_sys->p_jpeg.image_height = p_enc->fmt_in.video.i_visible_height;
+    p_sys->p_jpeg.input_components = 3;
+    p_sys->p_jpeg.in_color_space = JCS_YCbCr;
+
+    jpeg_set_defaults(&p_sys->p_jpeg);
+    jpeg_set_colorspace(&p_sys->p_jpeg, JCS_YCbCr);
+
+    p_sys->p_jpeg.raw_data_in = TRUE;
+    p_sys->p_jpeg.do_fancy_downsampling = FALSE;
+
+    jpeg_set_quality(&p_sys->p_jpeg, p_sys->i_quality, TRUE);
+
+    jpeg_start_compress(&p_sys->p_jpeg, TRUE);
+
+    /* Encode picture */
+    p_row_pointers = malloc(sizeof(JSAMPARRAY) * p_pic->i_planes);
+    if (p_row_pointers == NULL)
+    {
+        goto error;
+    }
+
+    for (int i = 0; i < p_pic->i_planes; i++)
+    {
+        p_row_pointers[i] = malloc(sizeof(JSAMPROW) * p_sys->p_jpeg.comp_info[i].v_samp_factor * DCTSIZE);
+    }
+
+    while (p_sys->p_jpeg.next_scanline < p_sys->p_jpeg.image_height)
+    {
+        for (int i = 0; i < p_pic->i_planes; i++)
+        {
+            int i_offset = p_sys->p_jpeg.next_scanline * p_sys->p_jpeg.comp_info[i].v_samp_factor / p_sys->p_jpeg.max_v_samp_factor;
+
+            for (int j = 0; j < p_sys->p_jpeg.comp_info[i].v_samp_factor * DCTSIZE; j++)
+            {
+                p_row_pointers[i][j] = p_pic->p[i].p_pixels + p_pic->p[i].i_pitch * (i_offset + j);
+            }
+        }
+        jpeg_write_raw_data(&p_sys->p_jpeg, p_row_pointers, p_sys->p_jpeg.max_v_samp_factor * DCTSIZE);
+    }
+
+    jpeg_finish_compress(&p_sys->p_jpeg);
+    jpeg_destroy_compress(&p_sys->p_jpeg);
+
+    for (int i = 0; i < p_pic->i_planes; i++)
+    {
+        free(p_row_pointers[i]);
+    }
+    free(p_row_pointers);
+
+    return p_block;
+
+error:
+    jpeg_destroy_compress(&p_sys->p_jpeg);
+
+    if (p_row_pointers != NULL)
+    {
+        for (int i = 0; i < p_pic->i_planes; i++)
+        {
+            free(p_row_pointers[i]);
+        }
+    }
+    free(p_row_pointers);
+
+    block_Release(p_block);
+
+    return NULL;
+}
+
+/*
+ * jpeg 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;
+
+    free(p_sys);
+}