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Jem Schofield
Jem Schofield

Jem Schofield is the founder of theC47, an online and offline resource focused on the craft of video production and filmmaking. He is a producer, author and educator & the director of The Filmmaker's Intensive, an annual two week program that focuses on narrative filmmaking.

On Set Data Management with the EOS C300

November 02, 2011

Working with Canon's XF Codec in Production

With the release of the EOS C300, producers, filmmakers and cinematographers now have a compact Super 35mm based digital cinema camera that can capture high definition film-like images to Compact Flash (CF) Cards using Canon's MPEG-2 4:2:2 50Mbps XF Codec. This codec was first introduced in Canon's XF series of professional HD Camcorders and is saved in the Material eXchange Format (MXF), which is compatible with all major non-linear editing (NLE), software.

This article will focus on the benefits of using Canon's 50Mbps 4:2:2 Constant Bit Rate (CBR), XF Codec and how you can work effectively with the codec using the EOS C300's CF card based system in production environments. While the EOS C300 is capable of recording at lower bit rates and resolutions, this article is about getting the most out of your camera when recording directly to the widely available, cost-effective and production proven media, CF cards.

Canon's XF Codec, Sound Format & MXF

The 50mbps, 4:2:2 codec used in the EOS C300 is based on the MPEG-2 Long GOP standard that has been adopted and used in many production and post-production workflows and environments. The codec's 4:2:2 color sampling is superior to 4:2:0 color sampling and allows for much greater flexibility in post-production when color correcting, grading and compositing footage. Sound is captured to the EOS C300 using uncompressed, Linear PCM audio.

As footage is being recorded to the EOS C300's CF cards, it is wrapped using the internationally standardized Material eXchange Format (MXF). The MXF container allows video, audio and important metadata to be wrapped into a single file and is used in both standard NLE workflows and with high-end network systems that are used by production studios and networks. As a standard solution, this format saves time and money over proprietary workflows. This helps make both the production and post-production process run smoothly.

Production Considerations

Whether on set or on location, integrity of your data is crucial. All of the money spent on a production is ultimately sitting on solid-state media (CF Cards). Without a good game plan you are risking the loss of an entire card's worth or up to an entire day's worth of footage.

It is important to not only think about how your data is going to be handled on set or on location, but also who is going to handle it. Today, that job is generally handled by a Digital Imaging Technician (DIT). Occasionally, it might be handled by a data wrangler or an assistant editor. In either case, there needs to be one person who is responsible for the successful recording and backing up of data.

Inserting and Initializing CF Cards

The EOS C300 records to readily available CF cards (see compatibility chart at the end of this article), and there are two card slots in the camera.

As with any camera system, the first steps to recording are to insert and then initialize the cards. Before doing so, make sure you turn the EOS C300's power dial to the "CAMERA" position.

  1. Open the CF card slot cover.
  2. Insert a CF card with the label facing up, all the way into the slot.
  3. Close the CF card slot cover. Don't force the cover closed. It should close easily as long as the card is inserted properly.
  4. In the EOS C300's Menu system, access Other Functions > Initialize Media CF A or Initialize CF B > Cancel / OK.
  5. Select [OK] and then press SET to initialize your card. When the confirmation message appears, press SET again.
  6. Repeat the process again for the other CF card/s (if applicable).

Note: While it is possible to initialize cards in one slot while another card is recording, it is generally a better practice to initialize (format), all of the cards that will be used in a day's shoot before actually recording. That would mean that if you were anticipating using six cards for a camera in a day, you should initialize and label all of those cards before shooting begins.

Bit Rate, Resolution and Frame Rate

Once your cards are initialized, the camera needs to be set up so that it records in the bit rate, resolution (frame size), and the frame rate that you want for your particular project. You also do this in the Other Functions menu.

  1. To set the bit rate and resolution in the EOS C300's Menu system, access Other Functions > Bit Rate/Resolution and set the desired bit rate & resolution (generally 50 Mbps 1920 x 1080). Once chosen, press SET.
  2. To choose the frame rate, access Other Functions > Frame Rate and choose your desired frame rate. If you are trying to achieve a film look, you should generally choose 24P (which runs at 23.98). There is also a True 24P option of you are shooting footage that needs to match projects that have been shot on other cameras (mainly film), that record at a true 24fps, but this option is usually reserved for very specific workflows and scenarios.
Recording Modes

You are now ready to record to the EOS C300's CF Cards. There are two main types of recording that you will generally use when shooting. The first is relay recording (the default mode in the camera), and the second is double-slot recording.

Note: You must insert two CF cards if you want to use either the Relay Recording or the Double Slot Recording modes of the camera.

Relay Recording

Relay recording supports spanning which means that as long as there are two cards in the camera, the recording will be relayed to the other card when one card is full. This mode of recording is ideal for documentary shoots, reality television and any project where long continuous recording times may be necessary. Two 32GB CF cards will let you record over 2 and a half hours of 4:2:2 footage at 50 Mbps.

When using relay recording, the CF Card slots are hot-swappable. This means that you can remove a full card in one slot and replace it with a fresh one while the other slot is recording to another card. Once that card is full, the EOS C300 switch over and will continue recording to the fresh card. You can then swap the full card out with a fresh one to effectively give you continuous recording for as long as you like. Recording is possible from card A to card B or from card B to card A.

Notes: 1) Relay recording can't be used during slow motion shooting with a bit rate setting of 50 Mbps. 2) A function to set relay recording ON or OFF is provided in the EOS C300's menu.

Double-Slot Recording

When integrity of data is absolutely crucial and there's no room for second takes, double-slot recording will simultaneously record the same data to both CF cards. This will create an instant back-up of what has been shot and is a best practice workflow on shoots where shorter record times are generally used and the costs of production are high.

To turn on double-slot recording access Other Functions > Double Slot Rec > On / Off. Once chosen, press SET.

In a double-slot recording scenario, the duplicate media can be immediately sent offsite for archiving or to be ingested and organized as part of the post-production process. Additionally, one card could be used to process dailies while the other is used to start post. As the cost of CF cards is low in comparison to some other proprietary media types, this is a viable workflow on many shoots.

It is not a requirement that the two cards being used in double-slot recording be the same storage capacity. If two cards of varying capacity are used during double-slot recording, recording time will simply be limited to the size of the smaller card.

Notes: 1) Double-slot recording can't be used together with relay or slow & fast motion recording. If double-slot recording and slow & fast motion recording are selected together, slow & fast motion will take precedence. 2) If the memory of one card is filled up before the memory of the other card is used up, the operation of recording onto both cards is stopped.

Clip Titles

It should be noted that when the EOS C300 record clips it assigns a 6-character clip name consisting of a 2-letter prefix and 4 numerals (for example, "AA0001"). The numerals of the clip name increase every time a new clip is recorded.

You can set the initial clip name in advance by using the Other Function > Clips menus. This will allow you to assign clip names whose metadata matches the job being produced.

  1. Other Functions > Clips > Title Prefix > AA-ZZ + 00-99
  2. Other Functions > Clips > Number Setting > Set (4-digit numeral)/Reset

Note: You cannot change a clip's name after it's been recorded. The video file (stream) in a clip will be split approximately every 2 GB for clips with long recording times.

Transferring & Backing Up Data

Before re-inserting a recorded CF card back into the EOS C300, it is extremely important that the data has been ingested and backed up to at least two separate locations. Ideally you wouldn't record onto a card more than once in a production day, but that is oftentimes unavoidable.

If you must re-record to a CF card during production, make sure that the recorded footage has been imported into your NLE and backed up properly. Refer to the user manual for more information on recommended post-production workflows.

CF Card Run Time Table

The following chart shows typical recording durations for CF cards, at different EOS C300 quality settings.

Card capacity 50Mb/s (CBR) 35Mb/s (VBR) 25Mb/s (CBR)
8 GB 20 min. 25 min. 40 min.
16 GB 40 min. 55 min. 80 min.
32 GB 80 min. 110 min. 155 min.
64 GB 160 min. 225 min. 310 min.
128GB 320 min. 445 min. 625 min.

CF Card Compatibility Table

The following chart shows EOS C300 compatible CF Cards.

Manufacturer Product name Capacity Model number Nominal Speed
SanDisk* ExtremePro 64GB SDCFXP-064G-J91 x600 (90MB/s)
32GB SDCFXP-032G-J91
16GB SDCFXP-016G-J91
Extreme 32GB SDCFX-032G-J61 x400 (60MB/s)
16GB SDCFX-016G-J61
8GB SDCFX-008G-J61
Z III 8GB HPC-CF8GZ3U5 x300 (45MB/s)
Lexar* Professional x300 16GB LCF16GBERBJP300 x300 (45MB/s)
Professional x600 16GB LCF16GBCRBJP600 x600 (90MB/s)
Delkin Devices** CombatFlash 32GB DDCFCOMBAT-32GB x625 (91MB/s)
Transcend** 600x CompactFlash Card 32GB TS32GCF600 x600 (90MB/s)
16GB TS16GCF600

Canon makes no representations or warranties with respect to any third party accessory or product mentioned herein.

*Fully operational in all modes.
**These cards compatible EXCEPT for slow motion recording

This chart was accurate at the time of publishing this article (Nov. 2011).


The Canon EOS C300 is an affordable and innovative digital cinema camera. By utilizing a tried and true codec that captures images at a 50 Mbps bit rate and 4:2:2 color sampling to industry standard CF cards, you will have greater flexibility in post-production to create the look you want.

By creating best practices on set, you will ensure that the data that you capture will be intact and ready for post. Create a standard workflow and you will be well on your way to capturing the images you imagine.

The CDLC contributors are compensated spokespersons and actual users of the Canon products that they promote.