ffmpeg

FFmpeg Best Practices

FFmpeg is the bedrock of our multimedia processing. Adhering to these guidelines ensures our implementations are secure, performant, and maintainable.

1. API-First for Application Integration

Always interact with FFmpeg via its libav* APIs (e.g., libavcodec, libavformat, libavfilter) for application-level logic. The ffmpeg command-line tool is for quick tests, scripting, or debugging, never for direct invocation within production application code.

❌ BAD: Shelling out to ffmpeg CLI from application code

import subprocess

# Insecure, slow, hard to manage errors, resource leaks
def transcode_video_bad(input_path, output_path):
    cmd = f"ffmpeg -i {input_path} -c:v libx264 -crf 23 {output_path}"
    subprocess.run(cmd, shell=True, check=True)

✅ GOOD: Using libav* APIs (conceptual C/C++)

#include <libavformat/avformat.h>
#include <libavcodec/avcodec.h>
// ... other libav* headers

// Proper API usage for transcoding (simplified for brevity)
int transcode_video_good(const char* input_path, const char* output_path) {
    AVFormatContext *input_ctx = NULL, *output_ctx = NULL;
    AVCodecContext *decoder_ctx = NULL, *encoder_ctx = NULL;
    // ... Initialize FFmpeg libraries
    // ... Open input file (avformat_open_input)
    // ... Find stream info (avformat_find_stream_info)
    // ... Find best video/audio stream (av_find_best_stream)
    // ... Allocate and open decoder context (avcodec_alloc_context3, avcodec_open2)
    // ... Allocate and open encoder context (avcodec_alloc_context3, avcodec_open2)
    // ... Open output file (avio_open, avformat_write_header)
    // ... Main loop: read packet, decode, filter, encode, write packet
    // ... Write trailer, cleanup (avformat_close_input, avio_closep, etc.)
    return 0; // Or error code
}

Rationale: Direct API calls offer fine-grained control, robust error handling, better resource management, and eliminate shell injection vulnerabilities.