This a python package providing tools for optimizing your over-the-top bitrate ladder per each video you need to encode.
You can configure a template encoding ladder with constraints (min/max bitrate) that will be respected for the output optimal ladder. You also have the control over analysis parameters (based on CRF encoding or multiple bitrate encodings with video quality metric assessments).
The CRF Analyzer This analyzer calculates an optimal bitrate for the higher profile. Other profiles are declined top to bottom from the initial gap between each profiles of the template ladder.
The Metric Analyzer This analyzer encodes multiple bitrates for each profile in the template ladder (from min to max, respecting a bitrate step defined by the user) It then calculates video quality metrics for each of these encodings (only ssim or psnr for now). The final optimized ladder will be constructed choosing for the best quality/bitrate ratio (similar to Netflix).
It is composed of multiple encoding profile object. Each encoding profile is defined by those attributes:
- width (int): Video definition width
- height (int): Video definition height
- bitrate_default (int): This should be the bitrate of your static encoding ladder
- bitrate_min (int): This is the minimal bitrate you set for this profile in the output optimized encoding ladder
- bitrate_max (int): This is the maximal bitrate you set for this profile in the output optimized encoding ladder
- required (bool): Indicates if you authorize the script to remove this profile if considered not useful after optimization (conditions for this to happen are explained after)
- bitrate_factor (float): this is a private attribute calculated after initialization of the template encoding ladder
| width | height | bitrate_default | bitrate_min | bitrate_max | required |
|---|---|---|---|---|---|
| in pixels | in pixels | in bits per second | in bits per second | in bits per second | bool |
| 1920 | 1080 | 4500000 | 2000000 | 6000000 | True |
| 1280 | 720 | 3400000 | 1300000 | 4500000 | True |
| 960 | 540 | 2100000 | 700000 | 3000000 | True |
| 640 | 360 | 1100000 | 300000 | 2000000 | True |
| 480 | 270 | 750000 | 300000 | 900000 | False |
| 480 | 270 | 300000 | 150000 | 500000 | True |
- How to choose the analysis parameters
- What is the multiple part analysis
- How is the weighted average bitrate calculated
- Documentation for the JSON ouput
This is package requires at least Python 3.4.
You need to have ffmpeg and ffprobe installed on the host running the script.
For libvmaf support install it with the help of official documentation. And build ffmpeg from source with following commands.
./configure --enable-libvmaf --enable-version3
make install
This is an example using the CRF Analyzer method.
# -*- coding: utf8 -*-
from pertitleanalysis import per_title_analysis as pta
# create your template encoding ladder
PROFILE_LIST = []
PROFILE_LIST.append(pta.EncodingProfile(1920, 1080, 4500000, 2000000, 6000000, True))
PROFILE_LIST.append(pta.EncodingProfile(1280, 720, 3400000, 1300000, 4500000, True))
PROFILE_LIST.append(pta.EncodingProfile(960, 540, 2100000, 700000, 300000, True))
PROFILE_LIST.append(pta.EncodingProfile(640, 360, 1100000, 300000, 2000000, True))
PROFILE_LIST.append(pta.EncodingProfile(480, 270, 750000, 300000, 900000, False))
PROFILE_LIST.append(pta.EncodingProfile(480, 270, 300000, 150000, 500000, True))
LADDER = pta.EncodingLadder(PROFILE_LIST)
# Create a new CRF analysis provider
ANALYSIS = pta.CrfAnalyzer("{{ your_input_file_path }}", LADDER)
# Launch various analysis
ANALYSIS.process(1, 1920, 1080, 23, 2)
ANALYSIS.process(10, 1920, 1080, 23, 2)
# Print results
print(ANALYSIS.get_json()){
"analyses": [
{
"average_bitrate": 3869192,
"optimized_encoding_ladder": {
"encoding_profiles": [
{
"bitrate": 3869192,
"bitrate_savings": 630808,
"height": 1080,
"width": 1920
},
{
"bitrate": 2923389,
"bitrate_savings": 476611,
"height": 720,
"width": 1280
},
{
"bitrate": 1805622,
"bitrate_savings": 294378,
"height": 540,
"width": 960
},
{
"bitrate": 945802,
"bitrate_savings": 154198,
"height": 360,
"width": 640
},
{
"bitrate": 644865,
"bitrate_savings": 105135,
"height": 270,
"width": 480
},
{
"bitrate": 257946,
"bitrate_savings": 42054,
"height": 270,
"width": 480
}
],
"overall_bitrate_ladder": 10446816,
"overall_bitrate_savings": 1703184
},
"optimal_bitrate": 3869192,
"parameters": {
"crf_value": 23,
"height": 1080,
"idr_interval": 2,
"method": "CRF",
"number_of_parts": 1,
"part_duration": 60.0,
"width": 1920
},
"processing_date": "2018-01-04 16:19:41.460371",
"standard_deviation": null
},
{
"average_bitrate": 3844318.1,
"optimized_encoding_ladder": {
"encoding_profiles": [
{
"bitrate": 4747733,
"bitrate_savings": -247733,
"height": 1080,
"width": 1920
},
{
"bitrate": 3587176,
"bitrate_savings": -187176,
"height": 720,
"width": 1280
},
{
"bitrate": 2100000,
"bitrate_savings": 0,
"height": 540,
"width": 960
},
{
"bitrate": 1160556,
"bitrate_savings": -60556,
"height": 360,
"width": 640
},
{
"bitrate": 791288,
"bitrate_savings": -41288,
"height": 270,
"width": 480
},
{
"bitrate": 316515,
"bitrate_savings": -16515,
"height": 270,
"width": 480
}
],
"overall_bitrate_ladder": 12703268,
"overall_bitrate_savings": -553268
},
"optimal_bitrate": 4747733.0,
"parameters": {
"crf_value": 23,
"height": 1080,
"idr_interval": 2,
"method": "CRF",
"number_of_parts": 10,
"part_duration": 6.0,
"width": 1920
},
"processing_date": "2018-01-04 16:20:32.904371",
"standard_deviation": 1372795.7042960383
}
],
"template_encoding_ladder": {
"encoding_profiles": [
{
"bitrate": 4500000,
"constraints": {
"bitrate_factor": 1.0,
"bitrate_max": 6000000,
"bitrate_min": 2000000,
"required": true
},
"height": 1080,
"width": 1920
},
{
"bitrate": 3400000,
"constraints": {
"bitrate_factor": 1.3235294117647058,
"bitrate_max": 4500000,
"bitrate_min": 1300000,
"required": true
},
"height": 720,
"width": 1280
},
{
"bitrate": 2100000,
"constraints": {
"bitrate_factor": 2.142857142857143,
"bitrate_max": 2100000,
"bitrate_min": 700000,
"required": true
},
"height": 540,
"width": 960
},
{
"bitrate": 1100000,
"constraints": {
"bitrate_factor": 4.090909090909091,
"bitrate_max": 2000000,
"bitrate_min": 300000,
"required": true
},
"height": 360,
"width": 640
},
{
"bitrate": 750000,
"constraints": {
"bitrate_factor": 6.0,
"bitrate_max": 900000,
"bitrate_min": 300000,
"required": false
},
"height": 270,
"width": 480
},
{
"bitrate": 300000,
"constraints": {
"bitrate_factor": 15.0,
"bitrate_max": 500000,
"bitrate_min": 150000,
"required": true
},
"height": 270,
"width": 480
}
],
"overall_bitrate_ladder": 12150000
},
"input_file_path": "{{ your_input_file_path }}"
}