media-expert（媒体专家）

Media Expert

Expert guidance for media production, content management systems, video streaming, broadcasting systems, and modern media technology solutions.

Core Concepts

Media Production

• Video production workflows
• Audio production and mixing
• Post-production and editing
• Visual effects (VFX)
• Color grading and correction
• Animation and motion graphics
• Live production

Streaming and Broadcasting

• Video streaming platforms
• Content Delivery Networks (CDN)
• Adaptive bitrate streaming
• Live broadcasting
• OTT (Over-the-Top) platforms
• Digital rights management (DRM)
• Transcoding and encoding

Technologies

• Media Asset Management (MAM)
• Digital Asset Management (DAM)
• Broadcast automation
• IP-based media production
• Cloud production workflows
• AI for content analysis
• Virtual production

Standards and Protocols

• SMPTE standards
• HLS (HTTP Live Streaming)
• DASH (Dynamic Adaptive Streaming over HTTP)
• RTMP/RTSP protocols
• NDI (Network Device Interface)
• MXF (Material Exchange Format)
• Metadata standards (Dublin Core, IPTC)

Content Management System

from dataclasses import dataclass
from datetime import datetime, timedelta
from typing import List, Optional, Dict
from decimal import Decimal
from enum import Enum
import hashlib

class MediaType(Enum):
    VIDEO = "video"
    AUDIO = "audio"
    IMAGE = "image"
    DOCUMENT = "document"

class AssetStatus(Enum):
    DRAFT = "draft"
    IN_REVIEW = "in_review"
    APPROVED = "approved"
    PUBLISHED = "published"
    ARCHIVED = "archived"

@dataclass
class MediaAsset:
    """Media asset information"""
    asset_id: str
    title: str
    description: str
    media_type: MediaType
    file_path: str
    file_size_bytes: int
    duration_seconds: Optional[float]
    resolution: Optional[str]  # e.g., "1920x1080"
    codec: Optional[str]
    bitrate_kbps: Optional[int]
    frame_rate: Optional[float]
    created_at: datetime
    created_by: str
    status: AssetStatus
    tags: List[str]
    metadata: Dict[str, str]
    checksum: str

@dataclass
class ContentPackage:
    """Content package for distribution"""
    package_id: str
    title: str
    assets: List[str]  # Asset IDs
    created_at: datetime
    scheduled_publish: Optional[datetime]
    expiration_date: Optional[datetime]
    distribution_channels: List[str]

class MediaAssetManagementSystem:
    """Media asset management and workflow"""

    def __init__(self):
        self.assets = {}
        self.packages = {}
        self.workflows = []

    def ingest_asset(self, file_path: str, metadata: dict) -> MediaAsset:
        """Ingest media asset into system"""
        # Calculate checksum
        checksum = self._calculate_checksum(file_path)

        # Extract technical metadata
        tech_metadata = self._extract_metadata(file_path)

        asset = MediaAsset(
            asset_id=self._generate_asset_id(),
            title=metadata['title'],
            description=metadata.get('description', ''),
            media_type=MediaType(metadata['media_type']),
            file_path=file_path,
            file_size_bytes=tech_metadata['file_size'],
            duration_seconds=tech_metadata.get('duration'),
            resolution=tech_metadata.get('resolution'),
            codec=tech_metadata.get('codec'),
            bitrate_kbps=tech_metadata.get('bitrate'),
            frame_rate=tech_metadata.get('frame_rate'),
            created_at=datetime.now(),
            created_by=metadata['created_by'],
            status=AssetStatus.DRAFT,
            tags=metadata.get('tags', []),
            metadata=metadata.get('custom_metadata', {}),
            checksum=checksum
        )

        self.assets[asset.asset_id] = asset

        # Trigger automated workflows
        self._trigger_workflows(asset)

        return asset

    def _extract_metadata(self, file_path: str) -> dict:
        """Extract technical metadata from media file"""
        # Would use ffprobe or similar tool
        # Simulated metadata
        return {
            'file_size': 1073741824,  # 1 GB
            'duration': 3600.0,  # 1 hour
            'resolution': '1920x1080',
            'codec': 'h264',
            'bitrate': 5000,
            'frame_rate': 29.97
        }

    def _calculate_checksum(self, file_path: str) -> str:
        """Calculate file checksum for integrity"""
        # In production, would read actual file
        return hashlib.sha256(file_path.encode()).hexdigest()

    def transcode_asset(self, asset_id: str, output_profiles: List[dict]) -> dict:
        """Transcode asset to multiple formats"""
        asset = self.assets.get(asset_id)
        if not asset:
            return {'error': 'Asset not found'}

        transcode_jobs = []

        for profile in output_profiles:
            job = {
                'job_id': self._generate_job_id(),
                'asset_id': asset_id,
                'profile_name': profile['name'],
                'target_resolution': profile['resolution'],
                'target_bitrate': profile['bitrate'],
                'target_codec': profile['codec'],
                'status': 'queued',
                'progress_percent': 0,
                'estimated_completion': datetime.now() + timedelta(hours=1)
            }
            transcode_jobs.append(job)

        return {
            'asset_id': asset_id,
            'transcode_jobs': transcode_jobs,
            'total_jobs': len(transcode_jobs)
        }

    def search_assets(self, query: dict) -> List[MediaAsset]:
        """Search assets by metadata"""
        results = []

        for asset in self.assets.values():
            match = True

            # Text search
            if 'keywords' in query:
                keywords = query['keywords'].lower()
                if keywords not in asset.title.lower() and keywords not in asset.description.lower():
                    match = False

            # Media type filter
            if 'media_type' in query and asset.media_type.value != query['media_type']:
                match = False

            # Status filter
            if 'status' in query and asset.status.value != query['status']:
                match = False

            # Tag filter
            if 'tags' in query:
                required_tags = set(query['tags'])
                asset_tags = set(asset.tags)
                if not required_tags.issubset(asset_tags):
                    match = False

            # Date range
            if 'created_after' in query and asset.created_at < query['created_after']:
                match = False

            if match:
                results.append(asset)

        return results

    def create_content_package(self, package_data: dict) -> ContentPackage:
        """Create content package for distribution"""
        package = ContentPackage(
            package_id=self._generate_package_id(),
            title=package_data['title'],
            assets=package_data['asset_ids'],
            created_at=datetime.now(),
            scheduled_publish=package_data.get('scheduled_publish'),
            expiration_date=package_data.get('expiration_date'),
            distribution_channels=package_data['channels']
        )

        self.packages[package.package_id] = package

        return package

    def analyze_content(self, asset_id: str) -> dict:
        """AI-powered content analysis"""
        asset = self.assets.get(asset_id)
        if not asset:
            return {'error': 'Asset not found'}

        # Simulate AI analysis
        analysis = {
            'asset_id': asset_id,
            'detected_objects': ['person', 'car', 'building'],
            'detected_scenes': ['outdoor', 'daytime', 'urban'],
            'faces_detected': 3,
            'speech_to_text': 'Transcribed content would appear here...',
            'sentiment': 'positive',
            'content_categories': ['news', 'documentary'],
            'suggested_tags': ['urban', 'interview', 'documentary'],
            'quality_score': 85.0
        }

        return analysis

    def _trigger_workflows(self, asset: MediaAsset):
        """Trigger automated workflows for asset"""
        # Trigger proxy generation, thumbnails, etc.
        pass

    def _generate_asset_id(self) -> str:
        import uuid
        return f"ASSET-{uuid.uuid4().hex[:12].upper()}"

    def _generate_package_id(self) -> str:
        import uuid
        return f"PKG-{uuid.uuid4().hex[:8].upper()}"

    def _generate_job_id(self) -> str:
        import uuid
        return f"JOB-{uuid.uuid4().hex[:8].upper()}"

Video Streaming Platform

class VideoStreamingPlatform:
    """Video streaming and delivery system"""

    def __init__(self):
        self.streams = {}
        self.viewers = {}
        self.cdn_nodes = {}

    def start_live_stream(self, stream_data: dict) -> dict:
        """Start live video stream"""
        stream_id = self._generate_stream_id()

        stream = {
            'stream_id': stream_id,
            'title': stream_data['title'],
            'description': stream_data.get('description', ''),
            'streamer_id': stream_data['streamer_id'],
            'status': 'live',
            'started_at': datetime.now(),
            'viewer_count': 0,
            'peak_viewers': 0,
            'ingest_url': f'rtmp://ingest.example.com/live/{stream_id}',
            'playback_urls': {
                'hls': f'https://cdn.example.com/live/{stream_id}/playlist.m3u8',
                'dash': f'https://cdn.example.com/live/{stream_id}/manifest.mpd'
            },
            'quality_profiles': ['1080p', '720p', '480p', '360p']
        }

        self.streams[stream_id] = stream

        return stream

    def generate_adaptive_bitrate_manifest(self, asset_id: str) -> dict:
        """Generate ABR manifest for adaptive streaming"""
        # Generate HLS manifest
        hls_variants = [
            {
                'bandwidth': 5000000,  # 5 Mbps
                'resolution': '1920x1080',
                'codecs': 'avc1.640028,mp4a.40.2',
                'url': f'1080p/playlist.m3u8'
            },
            {
                'bandwidth': 2800000,  # 2.8 Mbps
                'resolution': '1280x720',
                'codecs': 'avc1.64001f,mp4a.40.2',
                'url': f'720p/playlist.m3u8'
            },
            {
                'bandwidth': 1400000,  # 1.4 Mbps
                'resolution': '854x480',
                'codecs': 'avc1.64001e,mp4a.40.2',
                'url': f'480p/playlist.m3u8'
            },
            {
                'bandwidth': 800000,  # 800 Kbps
                'resolution': '640x360',
                'codecs': 'avc1.64001e,mp4a.40.2',
                'url': f'360p/playlist.m3u8'
            }
        ]

        return {
            'asset_id': asset_id,
            'protocol': 'hls',
            'master_playlist_url': f'https://cdn.example.com/vod/{asset_id}/master.m3u8',
            'variants': hls_variants
        }

    def track_viewer_metrics(self, stream_id: str, viewer_id: str) -> dict:
        """Track viewer engagement metrics"""
        metrics = {
            'stream_id': stream_id,
            'viewer_id': viewer_id,
            'watch_time_seconds': 3600,
            'buffer_events': 2,
            'average_bitrate': 3500000,
            'quality_switches': 5,
            'playback_start_time_ms': 1200,
            'errors': 0,
            'device_type': 'desktop',
            'browser': 'chrome'
        }

        # Calculate Quality of Experience (QoE)
        qoe_score = self._calculate_qoe(metrics)
        metrics['qoe_score'] = qoe_score

        return metrics

    def _calculate_qoe(self, metrics: dict) -> float:
        """Calculate Quality of Experience score"""
        score = 100.0

        # Penalize buffering
        score -= metrics['buffer_events'] * 5

        # Penalize startup time
        if metrics['playback_start_time_ms'] > 2000:
            score -= 10

        # Penalize errors
        score -= metrics['errors'] * 15

        return max(0.0, score)

    def implement_drm(self, asset_id: str, drm_config: dict) -> dict:
        """Implement Digital Rights Management"""
        drm = {
            'asset_id': asset_id,
            'drm_systems': {
                'widevine': {
                    'license_url': 'https://license.example.com/widevine',
                    'supported_levels': ['L1', 'L3']
                },
                'fairplay': {
                    'certificate_url': 'https://license.example.com/fairplay/cert',
                    'license_url': 'https://license.example.com/fairplay/license'
                },
                'playready': {
                    'license_url': 'https://license.example.com/playready'
                }
            },
            'encryption': 'AES-128-CTR',
            'key_rotation_interval': 3600  # seconds
        }

        return drm

    def optimize_cdn_delivery(self, asset_id: str, viewer_location: tuple) -> dict:
        """Optimize CDN delivery based on viewer location"""
        # Find nearest CDN edge node
        nearest_node = self._find_nearest_cdn_node(viewer_location)

        return {
            'asset_id': asset_id,
            'cdn_node': nearest_node['node_id'],
            'cdn_location': nearest_node['location'],
            'distance_km': nearest_node['distance'],
            'estimated_latency_ms': nearest_node['latency'],
            'delivery_url': f"https://{nearest_node['node_id']}.cdn.example.com/{asset_id}"
        }

    def _find_nearest_cdn_node(self, viewer_location: tuple) -> dict:
        """Find nearest CDN edge node to viewer"""
        # Would calculate actual distances to CDN nodes
        return {
            'node_id': 'edge-us-east-1',
            'location': 'Virginia, USA',
            'distance': 250,  # km
            'latency': 15  # ms
        }

    def _generate_stream_id(self) -> str:
        import uuid
        return f"STREAM-{uuid.uuid4().hex[:8].upper()}"

Broadcast Automation

class BroadcastAutomationSystem:
    """Broadcast scheduling and automation"""

    def __init__(self):
        self.schedule = []
        self.playlists = {}

    def create_broadcast_schedule(self, channel: str, date: datetime, programming: List[dict]) -> dict:
        """Create daily broadcast schedule"""
        schedule_items = []
        current_time = date.replace(hour=0, minute=0, second=0)

        for program in programming:
            item = {
                'channel': channel,
                'start_time': current_time,
                'end_time': current_time + timedelta(seconds=program['duration']),
                'program_title': program['title'],
                'asset_id': program['asset_id'],
                'type': program['type'],  # 'program', 'commercial', 'filler'
                'metadata': program.get('metadata', {})
            }

            schedule_items.append(item)
            current_time = item['end_time']

        self.schedule.extend(schedule_items)

        return {
            'channel': channel,
            'date': date.date().isoformat(),
            'total_items': len(schedule_items),
            'total_duration': (schedule_items[-1]['end_time'] - schedule_items[0]['start_time']).seconds,
            'schedule': schedule_items[:5]  # Return first 5 items
        }

    def generate_playlist(self, schedule_id: str) -> dict:
        """Generate playout playlist"""
        # Convert schedule to playout format
        playlist = {
            'playlist_id': self._generate_playlist_id(),
            'format': 'xml',  # or 'json'
            'items': []
        }

        return playlist

    def monitor_broadcast(self, channel: str) -> dict:
        """Monitor live broadcast status"""
        status = {
            'channel': channel,
            'on_air': True,
            'current_program': 'Evening News',
            'time_code': '00:15:32',
            'next_program': 'Sports Tonight',
            'next_program_in': 2728,  # seconds
            'signal_quality': {
                'video_ok': True,
                'audio_ok': True,
                'sync_ok': True
            },
            'alarms': []
        }

        return status

    def _generate_playlist_id(self) -> str:
        import uuid
        return f"PLAY-{uuid.uuid4().hex[:8].upper()}"

Best Practices

Media Production

• Use standardized workflows
• Implement version control
• Maintain proper backups
• Use collaborative tools
• Implement quality control
• Document production processes
• Use industry-standard formats

Content Management

• Implement robust metadata schema
• Use consistent naming conventions
• Enable full-text search
• Implement access controls
• Maintain audit trails
• Use automated workflows
• Implement archival policies

Streaming Delivery

• Use adaptive bitrate streaming
• Implement CDN for global delivery
• Monitor QoE metrics
• Optimize for mobile devices
• Implement DRM when required
• Use low-latency protocols for live
• Monitor buffer ratios

Broadcasting

• Implement redundant systems
• Automate scheduling
• Monitor signal quality
• Maintain emergency protocols
• Use backup playout systems
• Implement proper logging
• Conduct regular testing

Anti-Patterns

❌ No backup systems ❌ Poor metadata management ❌ Single bitrate streaming ❌ No CDN implementation ❌ Ignoring QoE metrics ❌ Manual scheduling processes ❌ No DRM for premium content ❌ Poor asset organization ❌ No disaster recovery plan

Resources

• SMPTE: https://www.smpte.org/
• Streaming Media: https://www.streamingmedia.com/
• NAB (National Association of Broadcasters): https://www.nab.org/
• EBU (European Broadcasting Union): https://www.ebu.ch/
• FFmpeg: https://ffmpeg.org/
• Video.js: https://videojs.com/
• OTT Standards: https://www.ott-standards.org/