/*
  * Videotoolbox hardware acceleration
  *
  * copyright (c) 2012 Sebastien Zwickert
  *
  * This file is part of FFmpeg.
  *
  * FFmpeg 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.
  *
  * FFmpeg 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 FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
 #include "config.h"

 #include "videotoolbox.h"
 #include "libavutil/hwcontext_videotoolbox.h"
 #include "vt_internal.h"

 #include "libavutil/avutil.h"

 #include "libavutil/hwcontext.h"

 #include "bytestream.h"

 #include "decode.h"

 #include "h264dec.h"

 #include "hevcdec.h"

 #include "mpegvideo.h"

 #include <TargetConditionals.h>

 #ifndef kVTVideoDecoderSpecification_RequireHardwareAcceleratedVideoDecoder
 #  define kVTVideoDecoderSpecification_RequireHardwareAcceleratedVideoDecoder CFSTR("RequireHardwareAcceleratedVideoDecoder")

 #endif
 

 #if !HAVE_KCMVIDEOCODECTYPE_HEVC
 enum { kCMVideoCodecType_HEVC = 'hvc1' };
 #endif
 

 #define VIDEOTOOLBOX_ESDS_EXTRADATA_PADDING  12
 
 static void videotoolbox_buffer_release(void *opaque, uint8_t *data)
 {
     CVPixelBufferRef cv_buffer = (CVImageBufferRef)data;
     CVPixelBufferRelease(cv_buffer);
 }
 
 static int videotoolbox_buffer_copy(VTContext *vtctx,
                                     const uint8_t *buffer,
                                     uint32_t size)
 {
     void *tmp;
 
     tmp = av_fast_realloc(vtctx->bitstream,
                          &vtctx->allocated_size,
                          size);
 
     if (!tmp)
         return AVERROR(ENOMEM);
 
     vtctx->bitstream = tmp;
     memcpy(vtctx->bitstream, buffer, size);
     vtctx->bitstream_size = size;
 
     return 0;
 }
 
 int ff_videotoolbox_alloc_frame(AVCodecContext *avctx, AVFrame *frame)
 {

     int ret = ff_attach_decode_data(frame);
     if (ret < 0)
         return ret;
 

     frame->width  = avctx->width;
     frame->height = avctx->height;
     frame->format = avctx->pix_fmt;
     frame->buf[0] = av_buffer_alloc(1);
 
     if (!frame->buf[0])
         return AVERROR(ENOMEM);
 
     return 0;
 }
 

 #define AV_W8(p, v) *(p) = (v)
 

 CFDataRef ff_videotoolbox_avcc_extradata_create(AVCodecContext *avctx)
 {

     VTContext *vtctx = avctx->internal->hwaccel_priv_data;

     H264Context *h = avctx->priv_data;

     CFDataRef data = NULL;

     uint8_t *p;

     int vt_extradata_size = 6 + 2 + h->ps.sps->data_size + 3 + h->ps.pps->data_size;

     uint8_t *vt_extradata = av_malloc(vt_extradata_size);
     if (!vt_extradata)
         return NULL;
 
     p = vt_extradata;
 
     AV_W8(p + 0, 1); /* version */

     AV_W8(p + 1, h->ps.sps->data[1]); /* profile */
     AV_W8(p + 2, h->ps.sps->data[2]); /* profile compat */
     AV_W8(p + 3, h->ps.sps->data[3]); /* level */

     AV_W8(p + 4, 0xff); /* 6 bits reserved (111111) + 2 bits nal size length - 3 (11) */
     AV_W8(p + 5, 0xe1); /* 3 bits reserved (111) + 5 bits number of sps (00001) */

     AV_WB16(p + 6, h->ps.sps->data_size);
     memcpy(p + 8, h->ps.sps->data, h->ps.sps->data_size);
     p += 8 + h->ps.sps->data_size;

     AV_W8(p + 0, 1); /* number of pps */

     AV_WB16(p + 1, h->ps.pps->data_size);
     memcpy(p + 3, h->ps.pps->data, h->ps.pps->data_size);

     p += 3 + h->ps.pps->data_size;

     av_assert0(p - vt_extradata == vt_extradata_size);
 

     // save sps header (profile/level) used to create decoder session,
     // so we can detect changes and recreate it.

     if (vtctx)
         memcpy(vtctx->sps, h->ps.sps->data + 1, 3);

     data = CFDataCreate(kCFAllocatorDefault, vt_extradata, vt_extradata_size);
     av_free(vt_extradata);

     return data;
 }
 

 CFDataRef ff_videotoolbox_hvcc_extradata_create(AVCodecContext *avctx)
 {
     HEVCContext *h = avctx->priv_data;
     const HEVCVPS *vps = (const HEVCVPS *)h->ps.vps_list[0]->data;
     const HEVCSPS *sps = (const HEVCSPS *)h->ps.sps_list[0]->data;
     int i, num_pps = 0;
     const HEVCPPS *pps = h->ps.pps;
     PTLCommon ptlc = vps->ptl.general_ptl;
     VUI vui = sps->vui;
     uint8_t parallelismType;
     CFDataRef data = NULL;
     uint8_t *p;
     int vt_extradata_size = 23 + 5 + vps->data_size + 5 + sps->data_size + 3;
     uint8_t *vt_extradata;
 

     for (i = 0; i < HEVC_MAX_PPS_COUNT; i++) {

         if (h->ps.pps_list[i]) {
             const HEVCPPS *pps = (const HEVCPPS *)h->ps.pps_list[i]->data;
             vt_extradata_size += 2 + pps->data_size;
             num_pps++;
         }
     }
 
     vt_extradata = av_malloc(vt_extradata_size);
     if (!vt_extradata)
         return NULL;
     p = vt_extradata;
 
     /* unsigned int(8) configurationVersion = 1; */
     AV_W8(p + 0, 1);
 
     /*
      * unsigned int(2) general_profile_space;
      * unsigned int(1) general_tier_flag;
      * unsigned int(5) general_profile_idc;
      */
     AV_W8(p + 1, ptlc.profile_space << 6 |
                  ptlc.tier_flag     << 5 |
                  ptlc.profile_idc);
 
     /* unsigned int(32) general_profile_compatibility_flags; */
     memcpy(p + 2, ptlc.profile_compatibility_flag, 4);
 
     /* unsigned int(48) general_constraint_indicator_flags; */
     AV_W8(p + 6, ptlc.progressive_source_flag    << 7 |
                  ptlc.interlaced_source_flag     << 6 |
                  ptlc.non_packed_constraint_flag << 5 |
                  ptlc.frame_only_constraint_flag << 4);
     AV_W8(p + 7, 0);
     AV_WN32(p + 8, 0);
 
     /* unsigned int(8) general_level_idc; */
     AV_W8(p + 12, ptlc.level_idc);
 
     /*
      * bit(4) reserved = ‘1111’b;
      * unsigned int(12) min_spatial_segmentation_idc;
      */
     AV_W8(p + 13, 0xf0 | (vui.min_spatial_segmentation_idc >> 4));
     AV_W8(p + 14, vui.min_spatial_segmentation_idc & 0xff);
 
     /*
      * bit(6) reserved = ‘111111’b;
      * unsigned int(2) parallelismType;
      */
     if (!vui.min_spatial_segmentation_idc)
         parallelismType = 0;
     else if (pps->entropy_coding_sync_enabled_flag && pps->tiles_enabled_flag)
         parallelismType = 0;
     else if (pps->entropy_coding_sync_enabled_flag)
         parallelismType = 3;
     else if (pps->tiles_enabled_flag)
         parallelismType = 2;
     else
         parallelismType = 1;
     AV_W8(p + 15, 0xfc | parallelismType);
 
     /*
      * bit(6) reserved = ‘111111’b;
      * unsigned int(2) chromaFormat;
      */
     AV_W8(p + 16, sps->chroma_format_idc | 0xfc);
 
     /*
      * bit(5) reserved = ‘11111’b;
      * unsigned int(3) bitDepthLumaMinus8;
      */
     AV_W8(p + 17, (sps->bit_depth - 8) | 0xfc);
 
     /*
      * bit(5) reserved = ‘11111’b;
      * unsigned int(3) bitDepthChromaMinus8;
      */
     AV_W8(p + 18, (sps->bit_depth_chroma - 8) | 0xfc);
 
     /* bit(16) avgFrameRate; */
     AV_WB16(p + 19, 0);
 
     /*
      * bit(2) constantFrameRate;
      * bit(3) numTemporalLayers;
      * bit(1) temporalIdNested;
      * unsigned int(2) lengthSizeMinusOne;
      */
     AV_W8(p + 21, 0                             << 6 |
                   sps->max_sub_layers           << 3 |
                   sps->temporal_id_nesting_flag << 2 |
                   3);
 
     /* unsigned int(8) numOfArrays; */
     AV_W8(p + 22, 3);
 
     p += 23;
     /* vps */
     /*
      * bit(1) array_completeness;
      * unsigned int(1) reserved = 0;
      * unsigned int(6) NAL_unit_type;
      */
     AV_W8(p, 1 << 7 |
              HEVC_NAL_VPS & 0x3f);
     /* unsigned int(16) numNalus; */
     AV_WB16(p + 1, 1);
     /* unsigned int(16) nalUnitLength; */
     AV_WB16(p + 3, vps->data_size);
     /* bit(8*nalUnitLength) nalUnit; */
     memcpy(p + 5, vps->data, vps->data_size);
     p += 5 + vps->data_size;
 
     /* sps */
     AV_W8(p, 1 << 7 |
              HEVC_NAL_SPS & 0x3f);
     AV_WB16(p + 1, 1);
     AV_WB16(p + 3, sps->data_size);
     memcpy(p + 5, sps->data, sps->data_size);
     p += 5 + sps->data_size;
 
     /* pps */
     AV_W8(p, 1 << 7 |
              HEVC_NAL_PPS & 0x3f);
     AV_WB16(p + 1, num_pps);
     p += 3;

     for (i = 0; i < HEVC_MAX_PPS_COUNT; i++) {

         if (h->ps.pps_list[i]) {
             const HEVCPPS *pps = (const HEVCPPS *)h->ps.pps_list[i]->data;
             AV_WB16(p, pps->data_size);
             memcpy(p + 2, pps->data, pps->data_size);
             p += 2 + pps->data_size;
         }
     }
 
     av_assert0(p - vt_extradata == vt_extradata_size);
 
     data = CFDataCreate(kCFAllocatorDefault, vt_extradata, vt_extradata_size);
     av_free(vt_extradata);
     return data;
 }
 

 int ff_videotoolbox_buffer_create(VTContext *vtctx, AVFrame *frame)
 {
     av_buffer_unref(&frame->buf[0]);
 
     frame->buf[0] = av_buffer_create((uint8_t*)vtctx->frame,
                                      sizeof(vtctx->frame),
                                      videotoolbox_buffer_release,
                                      NULL,
                                      AV_BUFFER_FLAG_READONLY);
     if (!frame->buf[0]) {
         return AVERROR(ENOMEM);
     }
 
     frame->data[3] = (uint8_t*)vtctx->frame;
     vtctx->frame = NULL;
 
     return 0;
 }
 
 int ff_videotoolbox_h264_start_frame(AVCodecContext *avctx,
                                      const uint8_t *buffer,
                                      uint32_t size)
 {
     VTContext *vtctx = avctx->internal->hwaccel_priv_data;
     H264Context *h  = avctx->priv_data;
 
     if (h->is_avc == 1) {
         return videotoolbox_buffer_copy(vtctx, buffer, size);
     }
 
     return 0;
 }
 

 static int videotoolbox_h264_decode_params(AVCodecContext *avctx,
                                            int type,
                                            const uint8_t *buffer,
                                            uint32_t size)
 {
     VTContext *vtctx = avctx->internal->hwaccel_priv_data;

     H264Context *h = avctx->priv_data;
 
     // save sps header (profile/level) used to create decoder session
     if (!vtctx->sps[0])
         memcpy(vtctx->sps, h->ps.sps->data + 1, 3);

 
     if (type == H264_NAL_SPS) {

         if (size > 4 && memcmp(vtctx->sps, buffer + 1, 3) != 0) {

             vtctx->reconfig_needed = true;

             memcpy(vtctx->sps, buffer + 1, 3);

         }
     }
 

     // pass-through SPS/PPS changes to the decoder

     return ff_videotoolbox_h264_decode_slice(avctx, buffer, size);
 }
 

 int ff_videotoolbox_h264_decode_slice(AVCodecContext *avctx,
                                       const uint8_t *buffer,
                                       uint32_t size)
 {
     VTContext *vtctx = avctx->internal->hwaccel_priv_data;
     H264Context *h  = avctx->priv_data;
     void *tmp;
 
     if (h->is_avc == 1)
         return 0;
 
     tmp = av_fast_realloc(vtctx->bitstream,
                           &vtctx->allocated_size,
                           vtctx->bitstream_size+size+4);
     if (!tmp)
         return AVERROR(ENOMEM);
 
     vtctx->bitstream = tmp;
 
     AV_WB32(vtctx->bitstream + vtctx->bitstream_size, size);
     memcpy(vtctx->bitstream + vtctx->bitstream_size + 4, buffer, size);
 
     vtctx->bitstream_size += size + 4;
 
     return 0;
 }
 
 int ff_videotoolbox_uninit(AVCodecContext *avctx)
 {
     VTContext *vtctx = avctx->internal->hwaccel_priv_data;
     if (vtctx) {
         av_freep(&vtctx->bitstream);
         if (vtctx->frame)
             CVPixelBufferRelease(vtctx->frame);
     }
 
     return 0;
 }
 
 #if CONFIG_VIDEOTOOLBOX

 // Return the AVVideotoolboxContext that matters currently. Where it comes from
 // depends on the API used.
 static AVVideotoolboxContext *videotoolbox_get_context(AVCodecContext *avctx)
 {
     // Somewhat tricky because the user can call av_videotoolbox_default_free()
     // at any time, even when the codec is closed.
     if (avctx->internal && avctx->internal->hwaccel_priv_data) {
         VTContext *vtctx = avctx->internal->hwaccel_priv_data;
         if (vtctx->vt_ctx)
             return vtctx->vt_ctx;
     }
     return avctx->hwaccel_context;
 }
 
 static int videotoolbox_buffer_create(AVCodecContext *avctx, AVFrame *frame)
 {
     VTContext *vtctx = avctx->internal->hwaccel_priv_data;
     CVPixelBufferRef pixbuf = (CVPixelBufferRef)vtctx->frame;
     OSType pixel_format = CVPixelBufferGetPixelFormatType(pixbuf);
     enum AVPixelFormat sw_format = av_map_videotoolbox_format_to_pixfmt(pixel_format);
     int width = CVPixelBufferGetWidth(pixbuf);
     int height = CVPixelBufferGetHeight(pixbuf);
     AVHWFramesContext *cached_frames;
     int ret;
 
     ret = ff_videotoolbox_buffer_create(vtctx, frame);
     if (ret < 0)
         return ret;
 
     // Old API code path.
     if (!vtctx->cached_hw_frames_ctx)
         return 0;
 
     cached_frames = (AVHWFramesContext*)vtctx->cached_hw_frames_ctx->data;
 
     if (cached_frames->sw_format != sw_format ||
         cached_frames->width != width ||
         cached_frames->height != height) {
         AVBufferRef *hw_frames_ctx = av_hwframe_ctx_alloc(cached_frames->device_ref);
         AVHWFramesContext *hw_frames;
         if (!hw_frames_ctx)
             return AVERROR(ENOMEM);
 
         hw_frames = (AVHWFramesContext*)hw_frames_ctx->data;
         hw_frames->format = cached_frames->format;
         hw_frames->sw_format = sw_format;
         hw_frames->width = width;
         hw_frames->height = height;
 
         ret = av_hwframe_ctx_init(hw_frames_ctx);
         if (ret < 0) {
             av_buffer_unref(&hw_frames_ctx);
             return ret;
         }
 
         av_buffer_unref(&vtctx->cached_hw_frames_ctx);
         vtctx->cached_hw_frames_ctx = hw_frames_ctx;
     }
 

     av_buffer_unref(&frame->hw_frames_ctx);

     frame->hw_frames_ctx = av_buffer_ref(vtctx->cached_hw_frames_ctx);
     if (!frame->hw_frames_ctx)
         return AVERROR(ENOMEM);
 
     return 0;
 }
 

 static void videotoolbox_write_mp4_descr_length(PutByteContext *pb, int length)
 {
     int i;
     uint8_t b;
 
     for (i = 3; i >= 0; i--) {
         b = (length >> (i * 7)) & 0x7F;
         if (i != 0)
             b |= 0x80;
 
         bytestream2_put_byteu(pb, b);
     }
 }
 
 static CFDataRef videotoolbox_esds_extradata_create(AVCodecContext *avctx)
 {
     CFDataRef data;
     uint8_t *rw_extradata;
     PutByteContext pb;
     int full_size = 3 + 5 + 13 + 5 + avctx->extradata_size + 3;
     // ES_DescrTag data + DecoderConfigDescrTag + data + DecSpecificInfoTag + size + SLConfigDescriptor
     int config_size = 13 + 5 + avctx->extradata_size;
     int s;
 
     if (!(rw_extradata = av_mallocz(full_size + VIDEOTOOLBOX_ESDS_EXTRADATA_PADDING)))
         return NULL;
 
     bytestream2_init_writer(&pb, rw_extradata, full_size + VIDEOTOOLBOX_ESDS_EXTRADATA_PADDING);
     bytestream2_put_byteu(&pb, 0);        // version
     bytestream2_put_ne24(&pb, 0);         // flags
 
     // elementary stream descriptor
     bytestream2_put_byteu(&pb, 0x03);     // ES_DescrTag
     videotoolbox_write_mp4_descr_length(&pb, full_size);
     bytestream2_put_ne16(&pb, 0);         // esid
     bytestream2_put_byteu(&pb, 0);        // stream priority (0-32)
 
     // decoder configuration descriptor
     bytestream2_put_byteu(&pb, 0x04);     // DecoderConfigDescrTag
     videotoolbox_write_mp4_descr_length(&pb, config_size);

     bytestream2_put_byteu(&pb, 32);       // object type indication. 32 = AV_CODEC_ID_MPEG4

     bytestream2_put_byteu(&pb, 0x11);     // stream type
     bytestream2_put_ne24(&pb, 0);         // buffer size
     bytestream2_put_ne32(&pb, 0);         // max bitrate
     bytestream2_put_ne32(&pb, 0);         // avg bitrate
 
     // decoder specific descriptor
     bytestream2_put_byteu(&pb, 0x05);     ///< DecSpecificInfoTag
     videotoolbox_write_mp4_descr_length(&pb, avctx->extradata_size);
 
     bytestream2_put_buffer(&pb, avctx->extradata, avctx->extradata_size);
 
     // SLConfigDescriptor
     bytestream2_put_byteu(&pb, 0x06);     // SLConfigDescrTag
     bytestream2_put_byteu(&pb, 0x01);     // length
     bytestream2_put_byteu(&pb, 0x02);     //
 
     s = bytestream2_size_p(&pb);
 
     data = CFDataCreate(kCFAllocatorDefault, rw_extradata, s);
 
     av_freep(&rw_extradata);
     return data;
 }
 
 static CMSampleBufferRef videotoolbox_sample_buffer_create(CMFormatDescriptionRef fmt_desc,
                                                            void *buffer,
                                                            int size)
 {
     OSStatus status;
     CMBlockBufferRef  block_buf;
     CMSampleBufferRef sample_buf;
 
     block_buf  = NULL;
     sample_buf = NULL;
 
     status = CMBlockBufferCreateWithMemoryBlock(kCFAllocatorDefault,// structureAllocator
                                                 buffer,             // memoryBlock
                                                 size,               // blockLength
                                                 kCFAllocatorNull,   // blockAllocator
                                                 NULL,               // customBlockSource
                                                 0,                  // offsetToData
                                                 size,               // dataLength
                                                 0,                  // flags
                                                 &block_buf);
 
     if (!status) {
         status = CMSampleBufferCreate(kCFAllocatorDefault,  // allocator
                                       block_buf,            // dataBuffer
                                       TRUE,                 // dataReady
                                       0,                    // makeDataReadyCallback
                                       0,                    // makeDataReadyRefcon
                                       fmt_desc,             // formatDescription
                                       1,                    // numSamples
                                       0,                    // numSampleTimingEntries
                                       NULL,                 // sampleTimingArray
                                       0,                    // numSampleSizeEntries
                                       NULL,                 // sampleSizeArray
                                       &sample_buf);
     }
 
     if (block_buf)
         CFRelease(block_buf);
 
     return sample_buf;
 }
 
 static void videotoolbox_decoder_callback(void *opaque,
                                           void *sourceFrameRefCon,
                                           OSStatus status,
                                           VTDecodeInfoFlags flags,
                                           CVImageBufferRef image_buffer,
                                           CMTime pts,
                                           CMTime duration)
 {
     AVCodecContext *avctx = opaque;
     VTContext *vtctx = avctx->internal->hwaccel_priv_data;
 
     if (vtctx->frame) {
         CVPixelBufferRelease(vtctx->frame);
         vtctx->frame = NULL;
     }
 
     if (!image_buffer) {
         av_log(NULL, AV_LOG_DEBUG, "vt decoder cb: output image buffer is null\n");
         return;
     }
 
     vtctx->frame = CVPixelBufferRetain(image_buffer);
 }
 
 static OSStatus videotoolbox_session_decode_frame(AVCodecContext *avctx)
 {
     OSStatus status;
     CMSampleBufferRef sample_buf;

     AVVideotoolboxContext *videotoolbox = videotoolbox_get_context(avctx);

     VTContext *vtctx = avctx->internal->hwaccel_priv_data;
 
     sample_buf = videotoolbox_sample_buffer_create(videotoolbox->cm_fmt_desc,
                                                    vtctx->bitstream,
                                                    vtctx->bitstream_size);
 
     if (!sample_buf)
         return -1;
 
     status = VTDecompressionSessionDecodeFrame(videotoolbox->session,
                                                sample_buf,
                                                0,       // decodeFlags
                                                NULL,    // sourceFrameRefCon
                                                0);      // infoFlagsOut
     if (status == noErr)
         status = VTDecompressionSessionWaitForAsynchronousFrames(videotoolbox->session);
 
     CFRelease(sample_buf);
 
     return status;
 }
 

 static CMVideoFormatDescriptionRef videotoolbox_format_desc_create(CMVideoCodecType codec_type,
                                                                    CFDictionaryRef decoder_spec,
                                                                    int width,
                                                                    int height)

 {

     CMFormatDescriptionRef cm_fmt_desc;

     OSStatus status;

     status = CMVideoFormatDescriptionCreate(kCFAllocatorDefault,
                                             codec_type,
                                             width,
                                             height,
                                             decoder_spec, // Dictionary of extension
                                             &cm_fmt_desc);

     if (status)
         return NULL;

     return cm_fmt_desc;

 }
 

 static CFDictionaryRef videotoolbox_buffer_attributes_create(int width,
                                                              int height,
                                                              OSType pix_fmt)

 {

     CFMutableDictionaryRef buffer_attributes;
     CFMutableDictionaryRef io_surface_properties;
     CFNumberRef cv_pix_fmt;
     CFNumberRef w;
     CFNumberRef h;

     w = CFNumberCreate(kCFAllocatorDefault, kCFNumberSInt32Type, &width);
     h = CFNumberCreate(kCFAllocatorDefault, kCFNumberSInt32Type, &height);
     cv_pix_fmt = CFNumberCreate(kCFAllocatorDefault, kCFNumberSInt32Type, &pix_fmt);

     buffer_attributes = CFDictionaryCreateMutable(kCFAllocatorDefault,
                                                   4,
                                                   &kCFTypeDictionaryKeyCallBacks,
                                                   &kCFTypeDictionaryValueCallBacks);
     io_surface_properties = CFDictionaryCreateMutable(kCFAllocatorDefault,
                                                       0,
                                                       &kCFTypeDictionaryKeyCallBacks,
                                                       &kCFTypeDictionaryValueCallBacks);

     if (pix_fmt)
         CFDictionarySetValue(buffer_attributes, kCVPixelBufferPixelFormatTypeKey, cv_pix_fmt);
     CFDictionarySetValue(buffer_attributes, kCVPixelBufferIOSurfacePropertiesKey, io_surface_properties);
     CFDictionarySetValue(buffer_attributes, kCVPixelBufferWidthKey, w);
     CFDictionarySetValue(buffer_attributes, kCVPixelBufferHeightKey, h);
 #if TARGET_OS_IPHONE
     CFDictionarySetValue(buffer_attributes, kCVPixelBufferOpenGLESCompatibilityKey, kCFBooleanTrue);
 #else
     CFDictionarySetValue(buffer_attributes, kCVPixelBufferIOSurfaceOpenGLTextureCompatibilityKey, kCFBooleanTrue);
 #endif

     CFRelease(io_surface_properties);
     CFRelease(cv_pix_fmt);
     CFRelease(w);
     CFRelease(h);

     return buffer_attributes;

 }
 
 static CFDictionaryRef videotoolbox_decoder_config_create(CMVideoCodecType codec_type,
                                                           AVCodecContext *avctx)
 {
     CFMutableDictionaryRef config_info = CFDictionaryCreateMutable(kCFAllocatorDefault,

                                                                    0,

                                                                    &kCFTypeDictionaryKeyCallBacks,
                                                                    &kCFTypeDictionaryValueCallBacks);
 
     CFDictionarySetValue(config_info,

                          kVTVideoDecoderSpecification_RequireHardwareAcceleratedVideoDecoder,

                          kCFBooleanTrue);
 

     CFMutableDictionaryRef avc_info;
     CFDataRef data = NULL;

     avc_info = CFDictionaryCreateMutable(kCFAllocatorDefault,
                                          1,
                                          &kCFTypeDictionaryKeyCallBacks,
                                          &kCFTypeDictionaryValueCallBacks);

     switch (codec_type) {
     case kCMVideoCodecType_MPEG4Video :
         if (avctx->extradata_size)
             data = videotoolbox_esds_extradata_create(avctx);

         if (data)

             CFDictionarySetValue(avc_info, CFSTR("esds"), data);
         break;
     case kCMVideoCodecType_H264 :
         data = ff_videotoolbox_avcc_extradata_create(avctx);
         if (data)
             CFDictionarySetValue(avc_info, CFSTR("avcC"), data);
         break;
     case kCMVideoCodecType_HEVC :
         data = ff_videotoolbox_hvcc_extradata_create(avctx);
         if (data)
             CFDictionarySetValue(avc_info, CFSTR("hvcC"), data);
         break;
     default:
         break;

     }

 
     CFDictionarySetValue(config_info,
             kCMFormatDescriptionExtension_SampleDescriptionExtensionAtoms,
             avc_info);
 
     if (data)
         CFRelease(data);
 
     CFRelease(avc_info);

     return config_info;
 }
 

 static int videotoolbox_start(AVCodecContext *avctx)

 {

     AVVideotoolboxContext *videotoolbox = videotoolbox_get_context(avctx);

     OSStatus status;
     VTDecompressionOutputCallbackRecord decoder_cb;
     CFDictionaryRef decoder_spec;
     CFDictionaryRef buf_attr;
 
     if (!videotoolbox) {
         av_log(avctx, AV_LOG_ERROR, "hwaccel context is not set\n");
         return -1;
     }
 
     switch( avctx->codec_id ) {
     case AV_CODEC_ID_H263 :
         videotoolbox->cm_codec_type = kCMVideoCodecType_H263;
         break;
     case AV_CODEC_ID_H264 :
         videotoolbox->cm_codec_type = kCMVideoCodecType_H264;
         break;

     case AV_CODEC_ID_HEVC :
         videotoolbox->cm_codec_type = kCMVideoCodecType_HEVC;
         break;

     case AV_CODEC_ID_MPEG1VIDEO :
         videotoolbox->cm_codec_type = kCMVideoCodecType_MPEG1Video;
         break;
     case AV_CODEC_ID_MPEG2VIDEO :
         videotoolbox->cm_codec_type = kCMVideoCodecType_MPEG2Video;
         break;
     case AV_CODEC_ID_MPEG4 :
         videotoolbox->cm_codec_type = kCMVideoCodecType_MPEG4Video;
         break;
     default :
         break;
     }
 
     decoder_spec = videotoolbox_decoder_config_create(videotoolbox->cm_codec_type, avctx);
 

     if (!decoder_spec) {
         av_log(avctx, AV_LOG_ERROR, "decoder specification creation failed\n");
         return -1;
     }
 

     videotoolbox->cm_fmt_desc = videotoolbox_format_desc_create(videotoolbox->cm_codec_type,

                                                                 decoder_spec,
                                                                 avctx->width,
                                                                 avctx->height);
     if (!videotoolbox->cm_fmt_desc) {
         if (decoder_spec)
             CFRelease(decoder_spec);
 
         av_log(avctx, AV_LOG_ERROR, "format description creation failed\n");
         return -1;
     }
 
     buf_attr = videotoolbox_buffer_attributes_create(avctx->width,
                                                      avctx->height,
                                                      videotoolbox->cv_pix_fmt_type);
 
     decoder_cb.decompressionOutputCallback = videotoolbox_decoder_callback;
     decoder_cb.decompressionOutputRefCon   = avctx;
 
     status = VTDecompressionSessionCreate(NULL,                      // allocator
                                           videotoolbox->cm_fmt_desc, // videoFormatDescription
                                           decoder_spec,              // videoDecoderSpecification
                                           buf_attr,                  // destinationImageBufferAttributes
                                           &decoder_cb,               // outputCallback
                                           &videotoolbox->session);   // decompressionSessionOut
 
     if (decoder_spec)
         CFRelease(decoder_spec);
     if (buf_attr)
         CFRelease(buf_attr);
 
     switch (status) {
     case kVTVideoDecoderNotAvailableNowErr:

         av_log(avctx, AV_LOG_VERBOSE, "VideoToolbox session not available.\n");
         return AVERROR(ENOSYS);

     case kVTVideoDecoderUnsupportedDataFormatErr:

         av_log(avctx, AV_LOG_VERBOSE, "VideoToolbox does not support this format.\n");

         return AVERROR(ENOSYS);
     case kVTVideoDecoderMalfunctionErr:

         av_log(avctx, AV_LOG_VERBOSE, "VideoToolbox malfunction.\n");

         return AVERROR(EINVAL);

     case kVTVideoDecoderBadDataErr:

         av_log(avctx, AV_LOG_VERBOSE, "VideoToolbox reported invalid data.\n");

         return AVERROR_INVALIDDATA;
     case 0:
         return 0;
     default:

         av_log(avctx, AV_LOG_VERBOSE, "Unknown VideoToolbox session creation error %u\n", (unsigned)status);

         return AVERROR_UNKNOWN;
     }
 }
 

 static void videotoolbox_stop(AVCodecContext *avctx)

 {

     AVVideotoolboxContext *videotoolbox = videotoolbox_get_context(avctx);

     if (!videotoolbox)
         return;

     if (videotoolbox->cm_fmt_desc) {

         CFRelease(videotoolbox->cm_fmt_desc);

         videotoolbox->cm_fmt_desc = NULL;
     }

     if (videotoolbox->session) {
         VTDecompressionSessionInvalidate(videotoolbox->session);
         CFRelease(videotoolbox->session);

         videotoolbox->session = NULL;

     }
 }
 

 static const char *videotoolbox_error_string(OSStatus status)
 {
     switch (status) {
         case kVTVideoDecoderBadDataErr:
             return "bad data";
         case kVTVideoDecoderMalfunctionErr:
             return "decoder malfunction";
         case kVTInvalidSessionErr:
             return "invalid session";
     }
     return "unknown";
 }
 
 static int videotoolbox_common_end_frame(AVCodecContext *avctx, AVFrame *frame)
 {
     OSStatus status;
     AVVideotoolboxContext *videotoolbox = videotoolbox_get_context(avctx);
     VTContext *vtctx = avctx->internal->hwaccel_priv_data;
 
     if (vtctx->reconfig_needed == true) {
         vtctx->reconfig_needed = false;
         av_log(avctx, AV_LOG_VERBOSE, "VideoToolbox decoder needs reconfig, restarting..\n");
         videotoolbox_stop(avctx);
         if (videotoolbox_start(avctx) != 0) {
             return AVERROR_EXTERNAL;
         }
     }
 
     if (!videotoolbox->session || !vtctx->bitstream || !vtctx->bitstream_size)
         return AVERROR_INVALIDDATA;
 
     status = videotoolbox_session_decode_frame(avctx);
     if (status != noErr) {
         if (status == kVTVideoDecoderMalfunctionErr || status == kVTInvalidSessionErr)
             vtctx->reconfig_needed = true;
         av_log(avctx, AV_LOG_ERROR, "Failed to decode frame (%s, %d)\n", videotoolbox_error_string(status), (int)status);
         return AVERROR_UNKNOWN;
     }
 
     if (!vtctx->frame) {
         vtctx->reconfig_needed = true;
         return AVERROR_UNKNOWN;
     }
 
     return videotoolbox_buffer_create(avctx, frame);
 }
 
 static int videotoolbox_h264_end_frame(AVCodecContext *avctx)
 {
     H264Context *h = avctx->priv_data;
     AVFrame *frame = h->cur_pic_ptr->f;
     VTContext *vtctx = avctx->internal->hwaccel_priv_data;
     int ret = videotoolbox_common_end_frame(avctx, frame);
     vtctx->bitstream_size = 0;
     return ret;
 }
 
 static int videotoolbox_hevc_decode_params(AVCodecContext *avctx,
                                            int type,
                                            const uint8_t *buffer,
                                            uint32_t size)
 {
     return ff_videotoolbox_h264_decode_slice(avctx, buffer, size);
 }
 
 static int videotoolbox_hevc_end_frame(AVCodecContext *avctx)
 {
     HEVCContext *h = avctx->priv_data;
     AVFrame *frame = h->ref->frame;
     VTContext *vtctx = avctx->internal->hwaccel_priv_data;
     int ret;
 
     ret = videotoolbox_common_end_frame(avctx, frame);
     vtctx->bitstream_size = 0;
     return ret;
 }
 
 static int videotoolbox_mpeg_start_frame(AVCodecContext *avctx,
                                          const uint8_t *buffer,
                                          uint32_t size)
 {
     VTContext *vtctx = avctx->internal->hwaccel_priv_data;
 
     return videotoolbox_buffer_copy(vtctx, buffer, size);
 }
 
 static int videotoolbox_mpeg_decode_slice(AVCodecContext *avctx,
                                           const uint8_t *buffer,
                                           uint32_t size)
 {
     return 0;
 }
 
 static int videotoolbox_mpeg_end_frame(AVCodecContext *avctx)
 {
     MpegEncContext *s = avctx->priv_data;
     AVFrame *frame = s->current_picture_ptr->f;
 
     return videotoolbox_common_end_frame(avctx, frame);
 }
 

 static int videotoolbox_uninit(AVCodecContext *avctx)
 {
     VTContext *vtctx = avctx->internal->hwaccel_priv_data;
     if (!vtctx)
         return 0;
 
     ff_videotoolbox_uninit(avctx);
 
     if (vtctx->vt_ctx)

         videotoolbox_stop(avctx);

 
     av_buffer_unref(&vtctx->cached_hw_frames_ctx);
     av_freep(&vtctx->vt_ctx);
 
     return 0;
 }
 
 static int videotoolbox_common_init(AVCodecContext *avctx)
 {
     VTContext *vtctx = avctx->internal->hwaccel_priv_data;
     AVHWFramesContext *hw_frames;
     int err;
 
     // Old API - do nothing.
     if (avctx->hwaccel_context)
         return 0;
 
     if (!avctx->hw_frames_ctx && !avctx->hw_device_ctx) {
         av_log(avctx, AV_LOG_ERROR,
                "Either hw_frames_ctx or hw_device_ctx must be set.\n");
         return AVERROR(EINVAL);
     }
 
     vtctx->vt_ctx = av_videotoolbox_alloc_context();
     if (!vtctx->vt_ctx) {
         err = AVERROR(ENOMEM);
         goto fail;
     }
 
     if (avctx->hw_frames_ctx) {
         hw_frames = (AVHWFramesContext*)avctx->hw_frames_ctx->data;
     } else {
         avctx->hw_frames_ctx = av_hwframe_ctx_alloc(avctx->hw_device_ctx);
         if (!avctx->hw_frames_ctx) {
             err = AVERROR(ENOMEM);
             goto fail;
         }
 
         hw_frames = (AVHWFramesContext*)avctx->hw_frames_ctx->data;
         hw_frames->format = AV_PIX_FMT_VIDEOTOOLBOX;
         hw_frames->sw_format = AV_PIX_FMT_NV12; // same as av_videotoolbox_alloc_context()
         hw_frames->width = avctx->width;
         hw_frames->height = avctx->height;
 
         err = av_hwframe_ctx_init(avctx->hw_frames_ctx);
         if (err < 0) {
             av_buffer_unref(&avctx->hw_frames_ctx);
             goto fail;
         }
     }
 
     vtctx->cached_hw_frames_ctx = av_buffer_ref(avctx->hw_frames_ctx);
     if (!vtctx->cached_hw_frames_ctx) {
         err = AVERROR(ENOMEM);
         goto fail;
     }
 
     vtctx->vt_ctx->cv_pix_fmt_type =
         av_map_videotoolbox_format_from_pixfmt(hw_frames->sw_format);
     if (!vtctx->vt_ctx->cv_pix_fmt_type) {
         av_log(avctx, AV_LOG_ERROR, "Unknown sw_format.\n");
         err = AVERROR(EINVAL);
         goto fail;
     }
 

     err = videotoolbox_start(avctx);

     if (err < 0)
         goto fail;
 
     return 0;
 
 fail:
     videotoolbox_uninit(avctx);
     return err;
 }
 

 static int videotoolbox_frame_params(AVCodecContext *avctx,
                                      AVBufferRef *hw_frames_ctx)
 {
     AVHWFramesContext *frames_ctx = (AVHWFramesContext*)hw_frames_ctx->data;
 
     frames_ctx->format            = AV_PIX_FMT_VIDEOTOOLBOX;
     frames_ctx->width             = avctx->coded_width;
     frames_ctx->height            = avctx->coded_height;
     frames_ctx->sw_format         = AV_PIX_FMT_NV12;
 
     return 0;
 }
 

 const AVHWAccel ff_h263_videotoolbox_hwaccel = {

     .name           = "h263_videotoolbox",
     .type           = AVMEDIA_TYPE_VIDEO,
     .id             = AV_CODEC_ID_H263,
     .pix_fmt        = AV_PIX_FMT_VIDEOTOOLBOX,
     .alloc_frame    = ff_videotoolbox_alloc_frame,
     .start_frame    = videotoolbox_mpeg_start_frame,
     .decode_slice   = videotoolbox_mpeg_decode_slice,
     .end_frame      = videotoolbox_mpeg_end_frame,

     .frame_params   = videotoolbox_frame_params,

     .init           = videotoolbox_common_init,
     .uninit         = videotoolbox_uninit,

     .priv_data_size = sizeof(VTContext),
 };
 

 const AVHWAccel ff_hevc_videotoolbox_hwaccel = {

     .name           = "hevc_videotoolbox",
     .type           = AVMEDIA_TYPE_VIDEO,
     .id             = AV_CODEC_ID_HEVC,
     .pix_fmt        = AV_PIX_FMT_VIDEOTOOLBOX,
     .alloc_frame    = ff_videotoolbox_alloc_frame,
     .start_frame    = ff_videotoolbox_h264_start_frame,
     .decode_slice   = ff_videotoolbox_h264_decode_slice,

     .decode_params  = videotoolbox_hevc_decode_params,

     .end_frame      = videotoolbox_hevc_end_frame,

     .frame_params   = videotoolbox_frame_params,

     .init           = videotoolbox_common_init,
     .uninit         = ff_videotoolbox_uninit,
     .priv_data_size = sizeof(VTContext),
 };
 

 const AVHWAccel ff_h264_videotoolbox_hwaccel = {

     .name           = "h264_videotoolbox",
     .type           = AVMEDIA_TYPE_VIDEO,
     .id             = AV_CODEC_ID_H264,
     .pix_fmt        = AV_PIX_FMT_VIDEOTOOLBOX,
     .alloc_frame    = ff_videotoolbox_alloc_frame,
     .start_frame    = ff_videotoolbox_h264_start_frame,
     .decode_slice   = ff_videotoolbox_h264_decode_slice,

     .decode_params  = videotoolbox_h264_decode_params,

     .end_frame      = videotoolbox_h264_end_frame,

     .frame_params   = videotoolbox_frame_params,

     .init           = videotoolbox_common_init,
     .uninit         = videotoolbox_uninit,

     .priv_data_size = sizeof(VTContext),
 };
 

 const AVHWAccel ff_mpeg1_videotoolbox_hwaccel = {

     .name           = "mpeg1_videotoolbox",
     .type           = AVMEDIA_TYPE_VIDEO,
     .id             = AV_CODEC_ID_MPEG1VIDEO,
     .pix_fmt        = AV_PIX_FMT_VIDEOTOOLBOX,
     .alloc_frame    = ff_videotoolbox_alloc_frame,
     .start_frame    = videotoolbox_mpeg_start_frame,
     .decode_slice   = videotoolbox_mpeg_decode_slice,
     .end_frame      = videotoolbox_mpeg_end_frame,

     .frame_params   = videotoolbox_frame_params,

     .init           = videotoolbox_common_init,
     .uninit         = videotoolbox_uninit,

     .priv_data_size = sizeof(VTContext),
 };
 

 const AVHWAccel ff_mpeg2_videotoolbox_hwaccel = {

     .name           = "mpeg2_videotoolbox",
     .type           = AVMEDIA_TYPE_VIDEO,
     .id             = AV_CODEC_ID_MPEG2VIDEO,
     .pix_fmt        = AV_PIX_FMT_VIDEOTOOLBOX,
     .alloc_frame    = ff_videotoolbox_alloc_frame,
     .start_frame    = videotoolbox_mpeg_start_frame,
     .decode_slice   = videotoolbox_mpeg_decode_slice,
     .end_frame      = videotoolbox_mpeg_end_frame,

     .frame_params   = videotoolbox_frame_params,

     .init           = videotoolbox_common_init,
     .uninit         = videotoolbox_uninit,

     .priv_data_size = sizeof(VTContext),
 };
 

 const AVHWAccel ff_mpeg4_videotoolbox_hwaccel = {

     .name           = "mpeg4_videotoolbox",
     .type           = AVMEDIA_TYPE_VIDEO,
     .id             = AV_CODEC_ID_MPEG4,
     .pix_fmt        = AV_PIX_FMT_VIDEOTOOLBOX,
     .alloc_frame    = ff_videotoolbox_alloc_frame,
     .start_frame    = videotoolbox_mpeg_start_frame,
     .decode_slice   = videotoolbox_mpeg_decode_slice,
     .end_frame      = videotoolbox_mpeg_end_frame,

     .frame_params   = videotoolbox_frame_params,

     .init           = videotoolbox_common_init,
     .uninit         = videotoolbox_uninit,

     .priv_data_size = sizeof(VTContext),
 };
 
 AVVideotoolboxContext *av_videotoolbox_alloc_context(void)
 {
     AVVideotoolboxContext *ret = av_mallocz(sizeof(*ret));
 
     if (ret) {
         ret->output_callback = videotoolbox_decoder_callback;
         ret->cv_pix_fmt_type = kCVPixelFormatType_420YpCbCr8BiPlanarVideoRange;
     }
 
     return ret;
 }
 
 int av_videotoolbox_default_init(AVCodecContext *avctx)
 {
     return av_videotoolbox_default_init2(avctx, NULL);
 }
 
 int av_videotoolbox_default_init2(AVCodecContext *avctx, AVVideotoolboxContext *vtctx)
 {
     avctx->hwaccel_context = vtctx ?: av_videotoolbox_alloc_context();
     if (!avctx->hwaccel_context)
         return AVERROR(ENOMEM);

     return videotoolbox_start(avctx);

 }
 
 void av_videotoolbox_default_free(AVCodecContext *avctx)
 {
 

     videotoolbox_stop(avctx);

     av_freep(&avctx->hwaccel_context);
 }
 #endif /* CONFIG_VIDEOTOOLBOX */